The door might conceivably be a trap. A trap does not have to be contrived in advance with some clearly defined purpose in mind. Circumstances can take a door or a window and turn it into a trap. A glove or a weapon left lying about can be picked up by an innocent man and snare him most damnably by seeming to point up his guilt. What purpose did the inner door serve? Did it open on a corridor leading back to the general passenger cabin? If it did, it wouldn't be a trap; it would simply have "blind alley" stamped all over it. Corriston suddenly realized that he was succumbing to a crazy kind of inaction. The door could lead almost anywhere, and if he had any sense at all he'd go through it fast. Go through it he did, in six long strides. He'd been right about one thing--the blind alley part. He found himself, in not quite total darkness, in what was unquestionably an intership passageway. There was just light enough for him to make out the shadowy walls on both sides of him. Rather they were like metal bulkheads that gave off just enough reflected light for him to see by. He wouldn't have considered ten or twelve seconds spent with a pocket flash a waste of time. But he had no pocket flash. The best he could do was stretch out both of his arms to determine just how far apart the bulkheads were. They were less than six feet apart. Well, no sense in measuring the walls. A girl he'd talked to and liked instantly had vanished in a dark world, and he knew now that there was more than mere liking in the way he felt about her. He didn't dare ask himself how much more, not in so confined a space and with his chances of finding her again dwindling with every second that passed. The passageway ended in a blank wall, less than forty feet from its beginning. Corriston saw the wall and was advancing toward it when he suddenly realized that the deck itself wasn't continuous. In his path, and almost directly underfoot, a companionway entrance yawned, so unexpectedly close that another short step would have sent him plunging into it. He saw the faint light reflected on its circumference and halted just in time to avoid a possibly fatal fall. He knelt and stared down into a spiraling web of darkness. He could see a faint glimmer of light on metal and knew that he was bending above either a circular staircase or a companionway ladder. It turned out to be a staircase. Down it he went, moving cautiously, holding on to the supporting guide rail as he descended deeper and deeper into the darkness. The darkness became almost absolute when the stairs ended. For a moment, at least, what appeared to be utter blackness engulfed him. Then gradually his vision became more effective. He could make out the faint outlines of stationary objects, of depths beyond depths, of crisscrossing lines and angles.