Another short corridor. Two well-equipped surgeries lined it. Both were shut down, cleaned up, night-silent. And windowless. A couple of storage rooms, one locked, one not. Two palm-locked laboratories; one had a bank of small animal cages at one end, that he could glimpse dimly through the glass. It was all crammed with equipment of the medical/biochemical sort, far more than a mere treatment clinic would require. The place fairly reeked of research.

How do I know—no. Don't ask. Just keep going. A lift-tube beckoned at the corridor's end. His body ached, breathing hurt, but he had to grab his chance. Go, go, go.

Wherever he was, he was at the very bottom of it. The tube's floor was at his feet. It rose into dimness, lit by panels reading S-3, S-2, S-1. The tube was switched off, its safety door locked across the opening. He slid it open manually, and considered his options. He could switch the tube on, and risk lighting up some security monitor panel somewhere (why could he picture such a thing?); or he could leave it off and climb the safety-ladder in secret. He tried one rung of the ladder; his vision blackened. He backed down carefully and switched on the tube.

He rose gently to level S-1, and swung out. A tiny foyer had one door, solid and blank. It opened before him, and closed behind him. He stared around what was obviously a junk-storage chamber, and turned back. His door had vanished into a blank wall.

It took him a full minute of frightened examination to convince himself his sputtering brain wasn't playing tricks on him. The door was disguised as the wall. And he'd just locked himself out. He patted it frantically all over, but it would not re-admit him. His bare feet were freezing on the polished concrete floor, and he was dizzy and dreadfully tired. He wanted to go back to bed. The frustration and fear were almost overwhelming, not that they were so vast, but that he was so weak.

You only want it 'cause you can't have it. Perverse. Go on, he told himself sternly. He made his way from support to support to the outer door of the storage chamber. It too was locked from the outside, he found out the hard way when it sealed behind him. Go on.

The storage room had opened onto another short corridor, centered around an ordinary lift-tube foyer. This level pretended to be the end of the line, Level B-2; openings marked B-1, G, 1, 2, and so on ascended out of sight. He went for the zero-point, G. G for Ground? Yes. He exited into a darkened lobby.