THE SERVICE LEVEL ================= The ladder ends at a narrow corridor. The first section looks homemade: conduit, old telephone cable, faded Wisconsin utility labels, vacuum tubes and military surplus hardware. Then human construction begins merging with something else. Wires disappear into surfaces with no connectors. Concrete gives way to black material that seems to drink the fluorescent light. On the wall: NODE 608 SURFACE MAINTENANCE NO PERSONNEL BELOW RETURN LINE The corridor branches toward clicking relays, an operator desk, a machine room and a door that should lead outside.