When Grace arrived at Dr. Hartmann's that night, she was so utterly astonished by the course which events had taken that she was scarcely able to think. What to do she could not even guess. Here was her husband, the man she loved, in the power of Dr. Hartmann, and there seemed nothing whatever that she could do to help him. Yet how could she go quietly to her room, when Richard might be in the gravest danger? On the other hand, to attempt any resistance, to let the doctor know, by any action on her part, that she and Duvall were working in conjunction, would result in nothing but further disaster. The thought flashed through her mind that by preserving her character of a patient, she might, in the morning, communicate with Mr. Phelps, and secure his assistance in obtaining Richard's freedom.

These considerations came and went in the few seconds required for the little party to enter the hall. Her husband went first. Dr. Hartmann stood aside to permit her to follow him. Duvall turned as she passed through the door, and she heard him whisper, in a voice scarcely audible, "Say nothing." It was the cue she desired. She extended her hand as the doctor came in. "Good-night, Mr. Brooks," she said, quite calmly. "Thank you for bringing me home. I hope we shall meet again, sometime."

"I hope so," Duvall remarked, indifferently, then turned to the doctor. "Now, monsieur, let us have done with this farce as quickly as possible. I have no time to waste."

"Nor have I. Good-night, Miss Ellicott." He nodded pleasantly to Grace as she ascended the stairs, then addressed one of the two attendants. "Where is Herr Mayer?" he asked.

"He is waiting for you in the laboratory, Herr Doctor," the man replied.

"Good! This way, if you please." He motioned down the hall. "Be so good, Mr. Brooks, as to proceed at once."

Duvall started off down the hall in no pleasant frame of mind. The whole affair had been bungled by his stupidity. He passed through the door which Hartmann presently opened at the end of the hall, and found himself in a long narrow passage, lit by a single electric lamp. Hartmann closed the door carefully behind him, and came on down the corridor, his footsteps echoing loudly on the concrete floor.

At the end of the corridor a second door confronted them. It was opened by a tall blond man, with a reddish mustache and brilliant blue eyes. "I heard you coming," he said, nodding to Hartmann, then looked keenly at Duvall. "So this is the fellow, eh? Where shall we take him?"

The doctor pointed to an iron door which faced that by which they had entered. Between the two doors ran a narrow corridor, with an iron staircase to the left, leading upward. "In here," he said, shortly, and going to the door, opened it with a key which he drew from his pocket.

Again Duvall cursed his stupidity. For a moment, thoughts of resistance crossed his mind but he at once realized the hopelessness of it, and followed the doctor into the room. The tall man brought up the rear, closing the door silently after him.

The room was pitch dark. In a moment, however, Hartmann had pressed an electric button, and a brilliant light flooded the place. Duvall looked about him curiously, and in that fleeting glance saw that the room was without windows of any kind, and that the walls, smooth and white, contained no openings whatever, except the door by which they had entered. The floor, as he could tell by its feel under his feet, was of cement. The room was bare of furniture, but he perceived a number of boxes and packing cases standing about the walls.

The instant the door was closed, Hartmann sprang at the detective and grasped his two wrists. The latter had always been considered a powerful man, but the arms and shoulders of the doctor were those of a Hercules. "Search him, Mayer," he said, as he pinned Duvall's wrists together in his iron grip.

The man addressed as Mayer at once began a systematic search of Duvall's person. With deft fingers he explored his pockets, felt the linings of his clothing, tore through the contents of his pocketbook. The opera hat had fallen to the floor, in the short struggle which ensued when the detective found himself in Hartmann's grasp. Mayer picked it up, glanced at it carelessly, then threw it angrily into a corner, where it rolled unobserved, into the shadow of a large box.

"There is nothing here," he said, in a voice of keen disappointment. "He must have hidden it elsewhere."

"In his room at the hotel, perhaps—his portmanteau," the doctor said, eagerly, releasing Duvall's hands and throwing him to one side with some violence.

Mayer looked grave. "I have searched everything thoroughly. It is not there."

The doctor muttered an oath. "The other—the old Frenchman?"

"He was arrested to-night on a charge of irregularity in his passport. Nothing discovered. He will be released in the morning."

"Teufel!" The doctor swore excitedly in German. "Then the other one—the one who was in charge of Seltz—he must have it."

"No. He also has been searched, with the same results."

"May I ask what you are looking for?" asked Duvall, calmly.

"You know, well enough, Duvall," exclaimed Mayer, turning on him. "Oh, yes—I know your name. The examination of your baggage showed that. As soon as I wired to London and discovered that the man Seltz had left there last night, I knew how we had been fooled. One of our men saw the snuff box in your possession just before you left the hotel to go to the house of Mr. Phelps. What have you done with it?"

Duvall regarded his questioner calmly. "I do not know what you are talking about, gentlemen. I have no snuff box, nor do I use tobacco in that form. And now, if you have concluded this outrage upon an American citizen, perhaps you will let me return quietly to my hotel. If you do not, I promise you you shall pay heavily for it."

His words, for the moment, seemed to disconcert the two men. Then Mayer laughed, "Nothing but bluff, young man—American bluff. I know who you are. You followed Seltz here from London, and got the snuff box from him by a trick. Now tell us where it is."

The detective smiled. "I do not know what you are talking about," he said, quietly.

Dr. Hartmann growled out an oath. "Take off his things, Mayer. He may have the box in his clothing somewhere—or the heel of his boot. I'll get a dressing-gown, from above." He left the room, and Duvall heard him clanking up the iron staircase.

"If you insist on removing my clothes," he said to Mayer, "I prefer to do so myself." He rapidly stripped off his evening suit and shoes, and threw them upon the floor.

The man gathered them up, feeling each article carefully, and testing the heels of the boots with a knife which he drew from his pocket. He appeared greatly disappointed at not finding the object of his search. Then he again examined Duvall, feeling his person from head to toe with great care. He had just finished when the doctor returned with a long gray woolen dressing gown, which he tossed to the detective.

"He's hidden it somewhere. He hasn't got it with him," Mayer exclaimed, angrily.

"Take him to the small bedroom in the west wing," said the doctor. "We'll get it out of him, before we're through. You can leave the clothes in the laboratory." He cast his eye about the room to see that nothing had been forgotten. Duvall trembled, thinking of the hat lying unseen behind the packing case in the corner. Hartmann, however, did not observe it. Without saying anything further he threw open the door, and they all passed into the little hall.

From there, Duvall was led up the iron staircase to the floor above, and found himself in a large room which he took to be the doctor's laboratory. It was dimly lit by means of a reading-lamp. He had a confused vision of a number of scientific appliances, bulking huge and forbidding in the shadows, and then was conducted through a glass door and along a corridor similar to the one through which he and the doctor had so recently passed on the floor below. He judged, from the direction they were taking, that it was directly above the lower passageway, and led back to the main part of the house.

In this he soon found that he was correct. A door at the end of the corridor gave entrance to the upper central hall of the main building. He was led off to the right, catching a momentary glimpse of a woman attendant sitting in a chair near the head of the stairs as he passed. In a few moments Hartmann paused before a door, threw it open, and turned on the lights. The detective saw before him a well-furnished bedroom, with two large windows, and another door, which he later found gave entrance to a bathroom. The dark shadows against the night light without showed him at once that the windows were barred.

He turned to the two men. "You do not intend to release me then?" he asked, angrily.

Hartmann laughed. "You will be quite comfortable here, my friend. I am sure that a few days of complete rest will benefit your condition greatly. I imagine your trouble is merely a temporary affliction—a loss of memory, let us say, an inability to recall your name. We'll soon have you all right again. You have only to inform me where you have placed the snuff box which you stole from my messenger this morning, and I shall know that a complete cure has been effected. If your friends are alarmed about you, it will be quite sufficient to tell them that you are in my care. Mr. Phelps, for instance, has complete confidence in my ability. I will make it a point to explain matters to him at once. Just a trifling ailment, a disordered condition of the brain cells. A week should set you right again. If there is anything you wish, the attendants will get it for you. Your clothes will be sent up from the hotel in the morning. Make yourself quite at home, I beg of you."

He turned away, with a sardonic smile, and Duvall heard the key turn in the door as it closed. He glanced at the barred windows, the door, half-open, leading to the bathroom, and realized that there was not the slightest hope of escape. Dr. Hartmann evidently intended to keep him a prisoner until he disclosed the whereabouts of the snuff box. He smiled grimly as he threw himself upon the bed. It seemed likely that his stay would be a long one.

After a time he began to think of Grace. How cleverly she had carried out her part! It was clear that the doctor did not suspect her, or, if he did, was unable to see where his suspicions led. How strange it seemed to realize that she, his wife, lay somewhere under the same roof with him—possibly even in the very next room! But thirty-six hours had passed since their wedding and their sudden and unexpected parting. During that time, he had seen Grace but twice, once, at Hartmann's office, in the morning; the second time, at the Minister's that night. How he had longed to touch her hand, to put his arms about her, to feel his lips on hers. Yet as matters stood, the chances of their seeing each other in the near future seemed particularly remote. He wondered if Hartmann would keep him a prisoner in his room. The morning, of course, would tell. He switched off the lights, got into bed, and after a long time fell into a broken sleep.

It was late in the afternoon, when Dr. Hartmann, through his man Mayer, discovered that Seltz had left London, and should have appeared at his office with the snuff box during the forenoon. A description of Seltz, together with a curious feeling of uneasiness which he felt after the departure of the man who had introduced himself as Mr. Brooks, caused him to conclude that he had been made the victim of a clever trick, and one which only his professional enthusiasm had made possible.

He at once set to work, through Mayer and his men, to locate Brooks. This was done, without difficulty, at the Hotel Metropole. While the doctor followed the latter to the Minister's, firm in his belief that he carried the snuff box with him, Mayer had arranged through certain connections with the Belgian police, to have Dufrenne arrested and placed in confinement over night on a trumped-up charge; Seltz liberated, and Lablanche held on a pretense of being concerned in the theft from the latter of a valuable package. A thorough search of Duvall's baggage—Dufrenne, it seemed, had none—disclosed nothing, except certain documents setting forth that the latter was Richard Duvall, an American citizen. It was these papers, in fact, which Duvall had shown to Mr. Phelps earlier in the day.

There was nothing to indicate to Hartmann that Duvall was acting in the interests of the French secret police, but the doctor suspected it, knowing as he did that the recovery of Monsieur de Grissac's snuff box would become at once a matter of the utmost moment to Lefevre and his men. Curiously enough, his momentary suspicions of Grace had largely disappeared. There was nothing to connect her with Duvall. He did not know that it was she who had opened the door and admitted Seltz to his house earlier in the day—he thought that Duvall had done this himself. Grace's manner, her conduct during the ride in the cab from the Minister's house, had shown him nothing. Still, he felt that she would bear watching and made his plans accordingly.

The sun was shining through the windows of Duvall's room when he awoke the next morning. For a brief space he was unable to recognize his surroundings, then the sequence of events came to him with a rush. He was conscious of a knocking at the door. He sprang up and opened it. Outside stood one of the men attendants whom he had seen the night before, with the portmanteau containing his clothes. The man placed the bag upon a chair, and opened it, then withdrew.

Duvall proceeded at once to dress. He had just finished when the attendant returned with an elaborate breakfast on a tray. He ate heartily. Evidently the doctor had no intention of starving him. Upon the table he observed his watch and seals, which he had worn with his evening clothes the night before. He looked at the watch and saw, to his astonishment, that it was after nine o'clock.

Now that he was dressed, he wondered what he should do with himself. It did not occur to him that the doctor would do other than keep him confined to his room, yet the man who had brought the breakfast things had not apparently locked the door when he went out.

Without any clear idea of what he intended to do, Duvall went to the door and tried it. To his surprise, he found it unlocked, and in a moment he had passed out into the hall.

The house seemed deserted. Even the attendant who had sat at the head of the stairs the night before was no longer in evidence. He went down to the lower floor without seeing any one. As he passed the door of the doctor's office, on his way to the entrance, he heard it open, and Dr. Hartmann looked out at him with a grim smile. "Ah—going for a stroll, I see, Mr. Duvall," he said, pleasantly enough. "It's a fine morning. I hope you enjoy it."

Duvall made no reply. He appreciated fully that Hartmann was only making fun of him, and realized his helplessness.

Once outside the door, he paused for a moment to drink in the beauty of the morning. Straight ahead of him stretched the driveway which led to the main road. The ornamental iron gate stood invitingly open. He went toward it, unconsciously pondering upon his situation and what he could do, if anything, to escape from it. At the gate he paused, looking about carefully to see whether his movements were observed. There appeared to be no one near him, although along one of the paths to the right of the house, he saw several persons walking, whom he judged to be inmates of the place. One or two others sat on benches among the shrubbery, reading. None of them seemed to take the least interest in his movements.

An empty cab passed slowly, the driver on the lookout for a fare. For a moment the detective thought of escape, his hand came up with a jerk to signal the cabman, then suddenly he let it fall with an exclamation of dismay. He could not escape—he did not dare attempt it, knowing that the snuff box, which had already caused him so much anxiety and trouble, lay in a corner of the room beneath the doctor's laboratory. First he must get that, before he could attempt to escape. He turned slowly back toward the house.

Then suddenly another doubt assailed him. Had not Dr. Hartmann allowed him this liberty merely to see whether or not he would take advantage of it? Would the latter conclude, now that he had failed to do so, that the snuff box was hidden somewhere on the premises? The thought disturbed him greatly.

Still another consideration occurred to him. If he made any attempt to recover the box, would his doing so not show his captors at once that they had overlooked the hat—a chance, indeed, in a thousand? The first move he might make toward the room under the laboratory, would arouse Hartmann's suspicions, a search would be made and the hat and its precious contents discovered.

Certainly he was tied hand and foot. He dared not leave the place, without taking the snuff box with him; he dared not attempt to recover it for fear its hiding place would thereby be disclosed. He was, he suddenly realized, as much a prisoner as though he were locked in a cell. And Grace?

The thought of her caused him to glance about nervously, and in a moment he saw her coming toward him from the direction of the house. She appeared to be looking for him, yet when she saw him, she seemed in doubt as to what to do. Duvall went up to her. "Good-morning, Miss Ellicott," he said, in a voice clearly audible within the house, were any of the windows open. He fancied he detected Hartmann's dark face peering at him from the waiting-room.

"Good-morning, Mr. Brooks," she said, affecting great surprise at seeing him. "You are here still?"

"Oh, yes." His tone was careless, but as he spoke he moved in a direction away from the house, and toward a small bench that stood beside the driveway. "Dr. Hartmann concluded that I needed treatment—I'm afflicted with loss of memory, it seems. Beautiful day, isn't it?"

She murmured some response, waiting for him to speak again. Presently he judged the distance from the house sufficiently great. No one was near enough to possibly overhear them.

"The snuff box is hidden—sewn inside of the false crown of my opera hat," he said, in a low voice. "It is in the room under the doctor's laboratory. He does not know it is there, and I don't dare try to get it, for fear he will find out. If you have a chance—" He paused.

"I understand."

"But be careful—very careful."

"I will." They sat down upon the bench toward which they had been headed. "I had thought of seeing Mr. Phelps to-day, and asking him to have you released."

"It would be useless," he said. "I cannot go without the snuff box."

"Shall I send word to our friends in Brussels?" she asked.

"How can you do that?"

She explained the method, by means of the boy who drove the delivery wagon. He considered the matter carefully. "Let them know that I am here, and why I cannot escape. Tell them that the snuff box is safe—so far. Do not let them know where it is—I trust no one with that—except you, dear."

The tenderness of his voice thrilled her. She longed to grasp his hand—to tell him of the love which filled her heart. Suddenly he spoke, quickly, warningly. "Be careful," he said. "We are being watched. That man Mayer is observing us with an opera glass, from a window of the house. Don't look at me that way. I shall leave you now. Let us meet during the afternoon." He rose, bowed to her carelessly, and strolled back toward the house, leaving her disconsolate upon the bench.

He entered the hall aimlessly, not knowing what to do next. The situation was one which taxed his resources to the utmost. No case that he had encountered in his whole experience offered the slightest suggestion whereby he might hope to effect a solution of his present difficulties. Courage, resource, ingenuity seemed alike useless. He was helpless.

Dr. Hartmann appeared in the hall as he entered it. "Come in, Mr. Duvall," he said, holding open the door of the office. "Suppose we have a little chat."

For a moment the detective hesitated, then decided to meet the doctor's good nature in kind. "By all means," he replied. "You owe me some explanation of your conduct in keeping me here."

"Keeping you here, Mr. Duvall? Surely you are mistaken. The gate is open." He waved his hand toward the lawn.

"I have no desire to run away, like a criminal, Dr. Hartmann. When I go, I shall go in a dignified way, and take my belongings with me."

"Your belongings!" The doctor seemed impressed with the remark. "So you have the snuff box hidden somewhere among them, have you?"

Duvall began a hasty denial, but the doctor cut him short. "Absurd, Mr. Duvall," he exclaimed. "You would leave here quickly enough, if you could take the box with you. But where you have concealed it, I confess I cannot imagine. I have examined your things with the utmost care. It is not among them, of that I am certain. I gave you your liberty this morning, to see whether or not you would attempt to escape. Had you done so I should have known that the box was concealed somewhere in the city, or else in the hands of your confederates. Now I am convinced that it is here. I thought at one time that you might have given it to Miss Ellicott—I have an idea that there is something between you, although of that I am by no means certain. But I know that she hasn't it, for her belongings were searched with equal care, last night, while she slept. The thing is a mystery to me, Mr. Duvall, and I compliment you upon your ingenuity. Had you been as wise, yesterday, as you were clever, you would have left Brussels before I discovered the trick you had played on me. Why you did not do so—why you foolishly remained to dine at the house of Mr. Phelps, I confess I cannot see. It is beyond me. But all that is beside the case. You have the snuff box—at least you know where it is. Are you going to turn it over to me, or must I force you to do so?"

Duvall listened to the doctor with an impassive face. "I know nothing about any snuff box," he returned, with a show of anger. "You are wasting your time, Dr. Hartmann. I have nothing more to say on the subject." He turned his back and gazed moodily out across the lawn.

Hartmann regarded him with a scowl of anger. "I give you until to-night, Mr. Duvall, to do as I ask. After that, I shall be compelled to force you to do so."

The detective shrugged his shoulders and turned to the door. "You use strong words, my friend. If any harm comes to me, my government will know how to deal with you." His threat did not seem to alarm the doctor particularly. "Do not forget, Mr. Duvall," he said, with an evil smile, "that while I know how to cure mental disorders, I also know how to create them. Good-morning."

The grave threat in his words filled Duvall with uneasiness. What did Hartmann mean? Did he propose to feed him with drugs, cunningly concealed in his food, which would steal away his senses, and leave him a babbling child? The thought was terrifying. Yet he had until to-night. He decided to return to his room and think, hoping thus to evolve some plan which might prove a solution of his difficulties. In the afternoon he would communicate it to Grace, and she, in return, could send word to Dufrenne, so that the latter might coöperate with him.

He found everything in his room as he had left it, and, seating himself by the window, was soon plunged in deep thought. The arrival of one of the attendants with his luncheon some two hours later woke him from a maze of profitless scheming. The problem was as yet still unsolved.

After luncheon, he decided to go down and have a talk with Grace. By keeping away from the house, and walking through the shrubbery, he hoped to be able to talk with her more freely. Much to his surprise, he found the door of his room once more locked. He sat down with a feeling of utter helplessness. The net was beginning to close about him.

Dinner was brought in at seven, and with it a small bottle of claret. He made an excellent meal, in spite of his unhappy reflections. The claret proved a welcome addition to it. On the tray was also a cigar. Decidedly the doctor was thoughtful, he reflected grimly.

Shortly after dinner he began to feel strangely drowsy. For a time he resisted the feeling—fought against it, but his eyelids seemed weighted with lead. Try as he would, he could not keep his eyes open. He threw up the window, gasping at the fresh air, but it had little effect. He rushed to the door, tried it, found it locked as he had expected, then groped toward the bed and fell heavily upon it, drunk with sleep. "It must have been the wine," he muttered to himself, and in another moment his muscles relaxed and he lay unconscious.

When Richard Duvall once more opened his eyes, he saw nothing but a blinding glare of light, that hurt and bewildered him with its singular and brilliant intensity. He closed his eyes again at once, unable to bear the irritation which was thus caused him. It was not exactly pain that he felt, but an intense discomfort, such as one experiences when looking directly at the brilliant rays of the sun.

After a few moments spent in futile attempts to cover his eyes with his hands, only to discover that his arms were tightly bound, he thought to secure relief by turning his face to one side, so that his vision might seek the soft darkness which seemed to lie on every side of him. In this effort he was equally unsuccessful. His head, his neck, his whole body, were rigid, immovable. He could not stir an inch in any direction.

He spent a long time in useless speculation upon the meaning of the remarkable situation in which he now found himself. He felt no pain, no discomfort, except that which the brilliance of the light above him caused. He determined at length once more to open his eyes, in order to discover if possible its source.

Even when his eyes were closed, he could see that the strange light burnt upon them. In a way it rendered his eyelids translucent—he was conscious of a dull pulsing redness through which shot a network of lines of fire. He opened his eyes slowly, cautiously, and looked upward. From some point above him, in what he judged must be the ceiling of the room, extended a beam of violet white light, cutting sharply through the darkness like the rays of a searchlight. At the opening in the ceiling through which it came, this beam was in diameter not more than two inches, but as it extended downward, it widened, taking the form of a long, thin, truncated cone, so that its width, where it impinged upon his face, was perhaps equal to twice that of a man's hand.

The darkness of the room about him made the beam of light seem a tangible, material thing. Its brilliance was unwavering—it extended from the ceiling to the surface of his face with the solidity, almost, of some huge, glittering icicle. He felt as though, were his hands but free, he could brush it aside, fling it off bodily into the darkness.

The effort of looking directly at the source of the light made his eyes smart with pain, but he found that by half-closing them, he could look off into the darkness, through the brilliant cone. In the pathway of its rays danced and tumbled innumerable dust specks—he knew then but for their presence, to afford the light a reflecting surface, its rays would be invisible to him.

In color the light was not yellow, like sunlight, but had a cold violet-blue quality, more nearly resembling moonlight. Its intensity, as well as the shape of the light cone, made him conclude that it was being focused through a powerful lens, or projected by means of a brilliant reflector.

He could imagine no possible reason for the situation in which he found himself. What the purpose of the beam of light was; why it thus focused upon his upturned face, he could not guess. He thought about it for many minutes, his eyes closed, his head straining restlessly toward the soft outer darkness. Presently there flashed into his mind Dr. Hartmann's words at their last meeting: "While I know how to cure mental disorders, I also know how to create them." The thought made him shudder. Was this, then, the explanation of his predicament? Somewhere he had read, not long before, a newspaper account of the investigations of certain Italian scientists, concerning the effect of the violet and ultra-violet light rays upon the cells of the brain. He could not recollect just what the conclusions had been, but he did remember that the newspaper article spoke of the popular superstition that moonlight could cause insanity. He knew Hartmann to be a scientist of vast ability and resource, and realized that back of the elaborate preparations he had evidently made must lie some sinister purpose.

For what seemed an eternity he lay thinking, unable to come to any rational conclusion. The distressing effect of the light rays increased, rather than diminished, as his nerves became more and more unstrung. It seemed, even with, his eyes closed, that he could feel the weight of the cone of light upon his face. The desire to escape from its searching glare became well-nigh irresistible. How long would this torture continue? He began to feel intensely tired and worn out and realized that could he but shut out the blinding brilliancy which enveloped him, he would sink exhausted to sleep. Sleep! He could no more sleep, under the present conditions, than he could fly to the moon. Then there came to his mind a recollection of a form of torture practised among the Chinese, the prevention of sleep. Prisoners, he had read, were confined in a cage, in brilliant sunlight, and prevented from sleeping by being prodded from without with spears. At the expiration of a week, he had read, the victim goes raving mad. Was this, then, Hartmann's intention?

Whatever the man did, he knew he would adopt only such methods as would involve him in no damaging consequences. He might be kept in his present situation until insanity ensued, and Hartmann with his reputation as a physician, a scientist, could calmly deny any story he might tell, putting it down to the wanderings of a disordered brain. He realized the cunning of the man, his care to use no physical violence. Should he, Duvall, under the strain of the torture which he realized lay before him, consent to disclose the whereabouts of the ivory snuff box, in return for his liberty, what could he do, in retaliation? Hartmann would calmly deny his story, and would doubtless produce witnesses, such as Mayer, to prove that the detective came to him for treatment for some slight mental disorder, some lapse of memory and that the exposure to the light rays had been but part of his usual treatment. Clearly the doctor had covered his tracks most successfully.

Throughout all these torturing thoughts, the figure of Grace came and went unceasingly. What would she do—what could she do, to aid him? He had warned her not to ask Mr. Phelps to take any steps looking to his release. He realized that were Hartmann to appear now, and give him his freedom, he would not dare to accept it. That the doctor might do this very thing was his greatest fear. If he should insist upon his leaving the place, what could he do, then, to recover Monsieur de Grissac's snuff box? He prayed fervently that Dufrenne and his companions might in some way work out a plan to set matters right.

Presently he fell to thinking of the snuff box, and its safety. How fortunate it seemed, that the doctor and his man Mayer had overlooked the opera hat. He wondered if they had thought of it since? It was clear that they had not, else he would no longer be kept a prisoner. What was the room beneath the laboratory used for? Its appearance had suggested that it was not used at all—a mere lumber-room, a place for storing boxes and crates. And then there flashed into his mind the thought, where was he now? From the apparent distance of the ceiling, as shown by the beam of light, he concluded that he was lying on the floor, a conclusion which the hardness and coldness of the surface beneath him amply proved. Evidently it was a floor of stone, or cement, not one of wood. A certain sense of familiarity in his surroundings came over him. The faint radiance which was diffused about him by the light cone showed the walls before and on either side of him to be of uniform blackness, unrelieved by any suggestion of windows. He strove with all his power to pierce the shadowy gloom, to come upon some point of recognition, but the darkness baffled him.

In one corner a huge shadow, bulking formless against the wall, suggested the packing case behind which his opera hat had been tossed by Mayer during the search the night before. The thought thrilled him with renewed hope. What more likely place, after all, for Hartmann's deviltries than this silent room beneath the laboratory? If he was lying there now, and chance of escape should come, he might even yet be able to take the missing snuff box with him.

The hours dragged interminably. He was conscious of a keen feeling of pain, a smarting irritation, in his eyes, which caused tiny streams of moisture to trickle beneath their lids and roll unheeded down his cheeks. The muscles of his neck became sore and swollen, from his incessant though useless effort to turn aside his head. A dull pain began to shoot insistently through his temples, and his limbs became numb and cold. The desire to escape from the relentless brilliance of the light cone became unbearable; he felt as though, if relief did not soon come, he would shriek out in a madness of terror. Then the hopelessness of doing so became apparent, and he nerved himself with all the power of his will to endure the ever-increasing torture. Yet this torture was, he knew, largely mental—the actual pain was by no means unbearable; it was only the dull, insistent pounding of the light rays upon his eyes, his brain, from which he longed to escape. With closed eyes and tensely drawn nerves, he waited, watching the endless play of the tracery of light in the dull redness of his eyelids.

The sudden sharp rattle of a key in the door, followed by the turning of the knob, told him that someone was entering the room. He had a momentary vision of a patch of light, yellow against the surrounding blackness, which disappeared almost instantly as the door was closed. Then he was conscious of a shadowy form beside him, and heard the smooth, modulated tones of Dr. Hartmann's voice.

"Well, Mr. Duvall," he said, "how goes the treatment? Memory any better this morning?"

He made no reply. The mockery in the doctor's voice roused him to sudden and bitter anger.

"I'm trying a new modification of the light treatment upon you," Hartmann went on, with a jarring laugh. "Dr. Mentone, of Milan, has great hopes of it. Wonderful thing, these violet rays! Have you read of their use in sterilizing milk? No? The subject would interest you. How is your mind this morning? Somewhat irritated, no doubt. Well, well, that will soon wear off. You've only been under the treatment six hours. Scarcely long enough to produce much effect. We'll make it ten, the next time. It is necessary to increase gradually, in order not to superinduce insanity." He went to a switch on the wall and pressed it, and instantly the cone of light disappeared. Another movement, and the room Was flooded with the yellow glow of an electric lamp, which seemed dingy and wan, compared with the cold brilliance which it displaced.

The dispelling of darkness brought to Duvall's brain a rush of sensations, among which the knowledge that he was once more in the lumber-room beneath the laboratory stood forth with overwhelming prominence. He glanced at Hartmann with reddened eyes. "Let me up, damn you!" he shouted.

The doctor bent over him, his face smiling. "Just a moment, Mr. Duvall. Have a little patience." He began to unbuckle several straps, and presently stood back, with a wave of his hand. "Get up," he said.

The detective's swollen muscles, his stiffened limbs, still retained the sensation of being bound; he scarcely realized that his bonds had been removed. Painfully he crawled to his feet, and stood before the doctor, blinking, trying to collect his faculties. On the floor lay a number of broad leather straps, secured to iron rings which had been let into the cement floor.

His first thought was to make a quick rush at his captor, and after overpowering him, secure the snuff box and dash from the place. His eyes must have shown something of his intention, for Hartmann, stepping back a pace, drew his right hand from his pocket. It contained an ugly-looking magazine pistol. "Don't attempt anything rash, Mr. Duvall. It would be useless. Even should you succeed in disposing of me, which I hardly think possible, you could not get away from my man Mayer, who is waiting in the corridor outside. Enough of this nonsense," he went on, scowling. "I mean to be quite frank with you, my friend. I intend to subject you to this device of mine—" he waved his hand toward the opening in the ceiling—"until you disclose the whereabouts of the snuff box. I know it is somewhere near at hand, either here or in Brussels, for your two assistants, whom I have had released, have been hanging about the place all the morning. If the violet rays have no other effect, they will at least prevent you from sleeping, and my experience shows that loss of sleep, if persisted in, will shatter the best set of nerves on earth. You know what the effect is, for six hours. The next time, as I said some little while ago, we shall try ten—and after that, longer periods, until the process becomes continuous. I am giving you these brief respites, at first, because I have not the least wish to drive you mad—all I ask is the snuff box which you took from my messenger Seltz. Give it up, and you can go at your convenience. But I must have it—even if I am obliged to drive you to the limit. I advise you to save yourself much suffering, and give it to me now."

The detective drew back his arm—his fist clenched. The impulse to drive it into Hartmann's face was overpowering. He turned abruptly on his heel, and made no reply.

Hartmann waited for a moment, then seeing that his prisoner was not disposed to answer, went toward the door. "Max," he called, opening it, "bring in the tray." The attendant at once entered with a waiter containing food, which he placed on a box near the door. "Is that all?" he asked. Hartmann nodded and the man withdrew.

"Think the matter over, Mr. Duvall," the doctor remarked, as he stepped across the threshold of the door. "I shall call upon you again, later in the day."

Duvall waited until the door had been closed and locked, and the doctor's footsteps had died away up the iron staircase. He heard them for a moment, on the floor of the room above, then all was quiet.

In a moment the detective had stepped to the large box in the corner, behind which lay, he believed, the discarded opera hat. At a glance, he saw that it was still there. He was about to stoop and pick it up, when a sudden fear swept over him. Suppose he was being watched. The doctor was in the room above. The presence in the room of the beam of light showed clearly that there must be an opening in the ceiling, into the laboratory. For all he knew, Hartmann might be observing his every movement. He stopped in his attempt to pick up the hat, and pretended to be greatly interested in the box and its contents. After making a careful examination of the labels upon it, he strolled carelessly back to the other side of the room, and ate the breakfast which the attendant had left. He supposed it to be breakfast, although he had no realization of the time. In a moment he felt for his watch, and found that it was still in his pocket. When he consulted it, however, he saw at once that it had run down.

After his meal, he began to feel terribly tired and sleepy. At first he fought off the feeling, realizing that his only hope of freedom lay in keeping awake, with all his senses alert. Then he thought of the nerve-racking hours through which he had just passed; the many more which were likely to follow, and decided that he must have rest at any cost. He threw himself upon the floor, his head pillowed upon his arm, and was soon sleeping the deep sleep which follows utter exhaustion.

All during the afternoon of the day upon which she had first met her husband during his confinement at Dr. Hartmann's, Grace Duvall wandered about the place, looking for him, waiting with growing fears for his appearance. When evening came, and she had failed to find him, she became greatly alarmed. In her excitement, she forgot the word she had agreed to send into Brussels by the boy who drove the delivery wagon, and was just returning to the house when she heard someone calling to her from the drive. She turned and saw that it was the bread boy, who had stopped his cart some little distance from the veranda.

"Mademoiselle," he called, "you have dropped your handkerchief." He pointed with his whip to a white object which lay in the roadway close beside the wheels of the cart. She had not dropped her handkerchief—she knew that it was at that moment tightly clenched in her left hand, but she understood.

"Thank you," she called, and hurried toward him. The boy, meanwhile, had climbed down from the wagon, and picking up the handkerchief, which he had himself secretly dropped, handed it to her, with a polite bow. She felt, as she clutched the bit of linen, that within it lay a note.

"He is here," she said quickly, in an undertone. "The box is safe. It is hidden. They have not yet discovered it. But I am afraid something terrible has happened to Mr. Duvall. Tell them to send help, quick." She turned away, and the boy mounted his box, whistling gayly, and at once drove off.

Grace hurried to her room, to examine the note within the handkerchief. She could hardly wait to see what it contained. The contents were a great disappointment to her. "Leave the house about ten o'clock to-morrow morning," it said. That was all. She had already decided to do this, in order to effect, if possible, her husband's release. So far as the snuff box was concerned, she felt that she did not care whether the doctor discovered it or not, if only she might know that Richard was safe. All during the evening she wandered aimlessly about the house, hoping each minute that she might come upon him, but her search was in vain. Richard Duvall seemed to have vanished completely.

Once she met the doctor, just as she had given up in despair and was returning to her room. He spoke pleasantly enough, asked her how she felt, and showed much concern that she had refused to eat any supper. "You must eat, mademoiselle," he told her. "Have you taken regularly the tonic I prescribed?" She nodded, not considering it necessary to inform him that she had carefully poured it, dose by dose, into the sink. For a moment she thought of asking him what had become of Mr. Brooks, but she feared to rouse his suspicions. "I'm feeling somewhat out of sorts," she said. "I'll be all right in the morning."

"I am gratified to observe," he remarked, as she left him, "that you had no tendency to walk in your sleep last night. I trust the improvement will continue. Good-night." She could not determine whether or not there lay any hidden meaning back of his words. His mirthless smile somehow made her feel uncomfortable.

His words, however, inspired her to form a new plan. She would go to the laboratory that night, if she could by any means escape the vigilance of the woman on guard in the hall, and find out, if possible, whether or not Richard was confined there. From the windows of her room, which faced the rear of the house, she could see plainly the small square brick building in which the laboratory was located. There were lights in the floor on a level with her windows—that, she knew, was the room in which she had seen Hartmann sitting at his desk, on the night of her arrival. But there were, she knew, rooms both above and below this one, and in the latter lay hidden the Ambassador's snuff box. Was Richard confined there, as well? She determined to find out.

The woman who sat on watch in the hall came to her room at half-past ten and looked in to see if she required anything. Grace, who was just getting into bed, told her that she did not, said good-night sleepily, and asked her to turn off the lights. The woman did so, and closing the door softly, retired.

Grace lay in bed a long time, wondering how she could get down the hall, and into the passageway leading to the laboratory, without being observed. There seemed no possible way of accomplishing this, yet she was determined to attempt it. Her thoughts were interrupted by the faint ringing of an electric bell. She knew it was the one in the hall, near where the nurse sat, by which any of the patients, desiring her presence during the night, might summon her to their rooms. Grace slipped out of bed, opened her door the slightest crack, so that she could command a view of the hall, and peered out. She saw the nurse coming toward her with a glass of water in her hand. She disappeared for a moment into a room across the corridor, then reappeared almost at once and resumed her seat at the head of the stairs.

Grace was disappointed. She had been on the point of starting out, when the woman's reappearance prevented her. She crouched on the floor beside her door, waiting until the nurse should again be summoned away.

She waited for hours. She heard the church bells in the city, far off and muffled, booming the hour of midnight. The nurse on the chair yawned and nodded. After what seemed an eternity, she heard one o'clock strike, and then two. The house was shrouded in silence. Her knees were cramped and cold, from contact with the floor; her whole body seemed sore, from the nervous tension of her position. She almost screamed, when the electric bell suddenly rang out again, its sound intensified by the stillness until it seemed as though it must wake everyone in the house.

The nurse rose sleepily, glanced at the indicator on the wall which informed her from which room the summons had come, and started down the corridor toward the west wing of the building. As she passed beyond the circle of light cast by the electric globe in the central hall, Grace pushed her door open and slipped noiselessly out. For a moment she hesitated, saw the woman enter a room midway of the corridor, then flew like the wind toward the door which gave entrance to the passageway leading to the laboratory. Her bare feet made no sound, she gained the door without being discovered, and in an instant had swung it open, and was standing in the long covered way outside. She drew the door to after her noiselessly, then sank upon her knees and listened. In a short while she heard the nurse come shuffling down the corridor, and the creaking of her chair as she sank heavily into it. So far, she felt that she was safe.

She advanced along the corridor with great caution. Her chief fear was that the door of the laboratory might be locked, in which case, she would be unable to proceed further. When she reached it, and felt it yield as she slowly turned the knob, she heaved a sigh of relief. In a moment she was in the laboratory.

The room was unlighted, save for a faint glow which came from a small black box in the center of the floor. She had no idea what this box was, but noticed that heavy wires ran to it, from each side, and that there were several protuberances upon its top, which shone like brass. She did not stop to examine it further, however, but looked about for some means of reaching the room below. The idea of recovering the snuff box had suddenly occurred to her. With that in her possession, Richard, she believed, need no longer hesitate to escape at the first opportunity. He had told her that it was hidden in the room beneath. She ran quickly down the steps which she observed in one corner, feeling a glow of excitement at the daring of her quest.

At the bottom of the stairs she found a narrow little corridor with a heavy door opening on it which she judged led into the room she desired to enter. The corridor was lighted by a single window at the end opposite the staircase, through which came a faint light from without.

She groped about in the semi-darkness until she found the knob of the door and slowly turned it, pressing her weight against the panels. It did not yield. With a sickening feeling of disappointment she realized that it was locked.

She stood still for a moment, wondering what she should do next. Suddenly she shuddered, and a horrible faintness came over her. From within the room she distinctly heard the slow moaning of someone evidently in great pain. Thoughts of Richard at once rushed through her mind; she flung herself on her knees, in an agony of fear, and sought frantically for the keyhole. At last she found it, and looked into the room. The sight that met her gaze sent her reeling backward. There lay Richard, her husband, upon the floor, his face encircled by a ring of blinding light, by which she could see, with frightful distinctness, the ghastly expression of his features, the lines of agony about his eyes and mouth.

For a moment she beat frantically upon the door, calling to him incoherently. She thought he did not hear her, for he did not turn his head. Then she stopped, frightened at what she had done. Suppose the doctor were to overhear her? Everything would be lost. There was but one chance for Richard now, she felt, and that lay with her. She would leave the house, in the morning, proceed at once to the Minister's, and tell him the whole story. Snuff box or no snuff box, she was determined to rescue her husband from his present situation, if it was not already too late.

For a long time she looked into the room, watching the face, grim and silent in the circle of light. She called to him over and over, softly, telling him of her plans, of her love for him, of her sorrow, but he seemed not to hear. But for the twitching of his face, and the low moans which he uttered from time to time, she might have supposed him dead.

How she got back to her room, she could scarcely have told. She staggered up the stairs into the laboratory, out along the corridor, and at last reached the door leading into the main building. She pushed this silently open, and gazed cautiously into the hall. The nurse sat in her chair, apparently asleep. With the utmost care, Grace managed to enter the hall, and to close the door behind her. Then seeing that the woman was rousing, she determined upon a bold plan. She opened her eyes wide, trying to give them a vacant, staring appearance, and with arms extended started toward the nurse.

The latter rose with an exclamation of alarm, then recognizing the sudden apparition as Grace, came up to her, took her by the arm, and led her back to her room. She sank helplessly upon the bed, and pretended to fall asleep. Whether the woman suspected her or not, she could not tell—she noticed that she locked the door, on leaving the room.

The hours until dawn seemed interminable. She lay in bed, praying that there might yet be time in which to save Richard from Hartmann's machinations. What it was that the latter was doing to him, she could not guess, but the look of agony on Duvall's face told her that his sufferings, from some cause, were very great.

After a long time the day broke, and she dressed and managed to choke down a little breakfast. She kept in her room until long after nine o'clock, not daring to leave the house before ten. Dr. Hartmann came in just as she was preparing to go. She saw him glance quickly toward her hat, as she put it on. "I'm going in to the city, this morning, doctor," she said, carelessly. "There are a few things I must get at one of the shops."

He nodded, as though the matter were quite unimportant. "You had another attack, last night, Miss Ellicott," he said. "I regret that the symptoms have recurred."

"Did I? What did I do?" she inquired, wide-eyed.

"Nothing, luckily. Walked down the corridor a short distance, the nurse tells me. She stopped you before you got very far." He regarded her with his keen professional look. "Strange—you do not appear abnormally nervous. I fear I shall have to begin the hypnotic treatment at once."

She paid but scant attention. If she could accomplish what she hoped, this morning, neither Dr. Hartmann nor his treatments would matter in the least to her. "I am sorry it will be necessary," she said, "but of course you know best."

When she left the grounds, she watched carefully to see if she was being followed, but there was nothing to indicate that such was the case. At the corner below, a small, youngish-looking man turned in behind her. He appeared to have been walking rapidly, but she had no particular reason to believe that he was following her.

She made at once for the center of the town, determined to walk the distance rather than wait to find a cab. On the way she passed several stores, and it occurred to her to stop in at one of them and buy a pair of gloves, to lend color to her excuses. She did so, and was just going out again when she suddenly came face to face with the young man she had thought was following her. "Miss Ellicott," he said, raising his hat, and as his hand was poised before her eyes, she saw on his finger a ring similar to the one which had been given her in Paris by Monsieur Lefevre, on the day of her departure. She colored, started to pass on, then stopped. "Good-morning," she gasped, faintly.

"I'm so glad to see you," he rattled on. "Don't you remember our being introduced, at dinner one night, in Paris. I'm delighted to meet you again. On your way down-town, I suppose?" His remark seemed a question. She answered it at once. "Yes, a little shopping to do, and then I thought of stopping at the house of some friends—the United States Minister," she added, by way of explanation.

The stranger bowed. "May I have the pleasure of accompanying you?" he asked. "I also am going in that direction."

Grace assented, and they went out together. At the door the man summoned a cab. "It is safer," he whispered. "We may be observed."

Once inside the cab, which was a closed one, the young man began to ply Grace with questions. "I am one of Monsieur Lefevre's men," he told her, noting her momentary hesitation. "Be quite frank, please, and tell me everything."

When she had finished her story, he sat in silence for a long time. Then he turned to her with a question which made her think he had suddenly lost his mind. "Has Dr. Hartmann a phonograph in the house?" he inquired.

"A phonograph?" she looked at him curiously.

"Yes—yes." His voice betrayed his excitement. "We must send a message to Mr. Duvall. Your windows overlook the room where he is confined. He may hear it. It is the only way."

"Yes," she said, after a moment's thought. "There is a phonograph in the library—a small one. It is seldom used. But Dr. Hartmann—"

"Listen to me," he interrupted, "and do exactly as I say. Pretend to be ill. Ask Dr. Hartmann's permission to have the instrument moved to your room. Then play the records which I am about to get for you."

She gazed at him, scarcely understanding. "But—" she began.

"Of course you will play other records, as well, but this one you must play often—as often as possible. I do not know that Mr. Duvall will understand what the message is—it is a chance, but we must take it. I myself do not understand it very clearly, but the suggestion comes from Monsieur Lefevre himself. You know him. He has your husband's safety at heart." He leaned out, giving a few rapid instructions to the cabman, and then once more turned to Grace.

"Do not visit the house of the United States Minister. It will be most unwise. As soon as he learns that Mr. Duvall and yourself are at Dr. Hartmann's house as spies, he will of necessity refuse to assist you further. Should he not do so, should he demand Mr. Duvall's release, nothing would be gained, since the snuff box would of necessity be left behind. Dr. Hartmann will not injure your husband—he is too anxious to get possession of the snuff box for that. We will try the phonograph, to-day, and if that means is unsuccessful, we must make an attempt to regain the box, and release your husband by force."

As he finished speaking, the cab drew up at a music store. The stranger sprang out, and in a few moments reappeared with a small package in his hand. He handed it to her, then removed his hat and bowed. "I would suggest, mademoiselle, that you return at once, and make use of this as I have directed. If anything further occurs, send word by the delivery boy to-night." He bowed, and walked rapidly down the street.

Grace sadly ordered the cabman to return to Dr. Hartmann's, and then sat back, her mind torn by conflicting emotions. The whole thing seemed inexplicably mysterious and confusing. Here was Richard, her husband, suffering she knew not what agonies at Dr. Hartmann's hands, and these people, who ought to be attempting to liberate him, asked her to play upon the phonograph. She tore open the package which the young man had handed her, and glanced at it eagerly. Its title told her no more than the stranger himself had done. She read it over and over, aimlessly. It was The Rosary.

The dull, heavy sleep into which Richard Duvall had fallen, after Dr. Hartmann had left him, was suddenly disturbed by the realization that someone had seized him roughly by the arms. He attempted to rise, struggling instinctively against the two men who, he dimly saw, were bending over him, but his resistance was useless. In a moment the leather straps which encircled his wrists and ankles had been drawn tight, and he felt himself being lifted bodily and deposited on the floor in the center of the room. At first he cried out, cursing his captors loudly, but an instant's reflection showed him how profitless his remonstrances were, and he allowed himself to be bound to the floor in silence. In a moment, Dr. Hartmann—the detective saw that it was he, with Mayer—had switched on the violet light, and he once more felt its blinding radiance upon his face.

Hartmann opened the door. "I shall be back again in a few hours," he said, as he left the room. "I hope that by that time you will have quite recovered your senses."

The detective made no reply. He had definitely made up his mind upon one point: he was not going to purchase his freedom at the expense of his duty. The unfortunate situation in which he now found himself was, he knew very well, entirely his own fault, and his desire to atone for his momentary carelessness made him determined not to accede to Dr. Hartmann's demands. He hoped that his friends outside—Lablanche, Dufrenne, even Grace—might be able to come to his assistance. If he could only know that the snuff box was safe in Monsieur Lefevre's hands, the rest did not matter much.

These thoughts passed through his mind as he lay with closed eyes, his face quivering under the dazzling light which fell upon it. Its intensity was, he thought, greater, if anything, than it had been before, and the irritating effect upon his eyes more pronounced. He did not open his eyes at all, on this occasion, for fear even a momentary exposure would increase their sensitiveness.

Slowly the day passed. He concluded that it was afternoon, when he heard far off a bell striking the hour of two, although it might equally well have been two o'clock in the morning, for all he could tell. There was a faint hum of conversation in the laboratory above him, which convinced him that it was still day.

Presently his ear, acutely sensitive to the slightest noise which might disturb the stillness about him, became aware of a faint sound of music, which seemed to come to him from a long distance off. It was a popular French march, and from a certain quality of the notes he concluded that it was being played upon a phonograph. The strains of the music distracted him, took his mind from the things about him, and as he listened to it, it seemed that the effort of keeping his eyes tightly closed grew sensibly less, the blinding pressure of the unwavering light cone upon his face appreciably easier to bear. He knew that this was but a momentary relief, but he welcomed it eagerly. Lying in this terrifying silence, under the cruel glare of light, had become frightful—he wondered if, after all, his nerves, his mind, could long stand the strain.

The music stopped suddenly. He found himself eagerly hoping that there would be more. In a few moments it began again, and he was listening to the familiar strains of The Rosary. He had always liked the song—Grace, too, had been fond of it. He wondered if she could be playing to him, trying to soothe his fast-shattering nerves with music. It pleased him to think that it might be so, although he had no reason to suppose that Grace knew of the torture to which Dr. Hartmann was subjecting him.

After a time, the final strains of The Rosary died away, to be followed by a German march, played by some military band. This, too, he was glad to hear, although he found himself thinking that he preferred The Rosary. As if in answer to his thoughts, it began again—he found himself repeating the words to himself mechanically, and thinking of Grace.

The music continued for long over an hour. Duvall noted with surprise that while there were many other selections, The Rosary was played almost every other time. So often, in fact, did its strains break the stillness, that he became annoyed—in his nervous state this constant repetition of the song worried him. After a time he shuddered when he heard it, hoping that each time would be the last. No one but an imbecile, he muttered to himself, could enjoy playing a piece over and over in that aimless fashion. When at last the impromptu concert had ceased, and the silence about him was once more unbroken, he found himself puzzling in vain over the matter, as though it had become of vast importance to him.

After the music ceased, he realized how much it had helped him to endure the two or more hours which had elapsed since Hartmann left him. His real tortures were only just beginning. The constant blaze of light on his face, the ceaseless effort to keep his eyes closed, to turn his head away, in spite of the bonds which prevented it, once more almost frenzied him. He fell to wondering whether Hartmann had been in earnest, when he told him of the qualities of the violet rays. Could they in any way affect his mind? The mere thought stimulated his imagination to such an extent that already he was convinced that his senses were wandering—that his mind was becoming sluggish and dull.

As hour after hour passed, this thought became almost a certainty. His head began again to ache terribly, his eyes seemed to swim in pools of liquid fire. Bright flashes of light darted through his brain, and at times it seemed almost on fire. The pain which the constant effort to turn his head caused, was becoming more acute as each minute passed—he felt constantly on the point of screaming out in terror—begging for release—agreeing to do anything they asked of him. Then with a mighty effort of the will he would calm himself, and closing his eyes tightly once more, determine to endure until the end.

After an interminable period, the sound of the music once more fell upon his troubled brain. This time the strains sounded more distinct and clear. Three times in rapid succession The Rosary was played, then sudden silence. He waited in vain for more—dreading the recurrence of the song, yet expecting it, as one expects the continuance of any oft-repeated sound. There was nothing further, however, and once more the silence became like the darkness about him, a grim and positive thing.

Hours later, when his brain reeled endlessly in a blazing redness, and his tortured eyes seemed bursting from their sockets, the cone of violet light vanished as though some silent hand had brushed it aside, and in the reaction he fainted.

He awoke again to find himself lying on the floor, with Hartmann bending over him, feeling his pulse. In a fit of rage, he struck out with his clenched hand, and missing, scrambled to his feet. The room was faintly lit by the single electric globe, and he saw Mayer and Dr. Hartmann confronting him, the latter with a revolver in his hand. Once more he realized the futility of resistance, and sank against a packing box, his hand covering his burning eyes.

The latter appeared to be no longer in his former state of sardonic good nature. "Are you ready to tell us what you have done with the box?" he snarled.

Duvall made no reply, and this angered the doctor still further. "I'll give you an hour to think the matter over," he said, furiously. "And if you don't come to terms by that time, you shall stay under the influence of the light until you do." He turned toward the door, followed by Mayer, and in a moment they had left the room.

Duvall, in his pain and distress, realized that something would have to be done at once, within the next hour, in fact, or he would be obliged to give up. Physical torture he could stand, but to lie here silently, under that cruel radiance, and realize that his brain was slowly giving way, he felt he could not endure.

Yet what was there that he could do? The walls of the room, of solid brick, he could not hope to penetrate. The door, of iron, a dozen men could not break through. He forced his shoulder against it, and laughed bitterly as he realized that with all his strength he could not even cause it to give the fraction of an inch. He determined to get the snuff box—to examine it—reckless of his fear of being observed. In a moment he had snatched the opera hat from the corner, torn out the lining, and held the box in his hand.

He paused for a moment, listening intently. Everything about him was still. There were no sounds from the laboratory above. He remembered now that he had not heard Hartmann and his companion ascend the iron stairway. Doubtless they had returned to the main building by means of the lower corridor.