The odor which came to his nostrils was equally unnerving. It was sharp, acrid, but with a faint mustiness about it which made him think of tomb rot. For a moment there was no sound at all, no faintest stir of movement. Then he heard a rustling sound that seemed to come from deep within the darkness. A rustling, a shuffling, the kind of sound that could have been made by a snake unwinding its coils, or someone dragging a heavy sack over a stone floor, or by nothing more unnerving than the slow backward and forward movements of a broom. Loring did not think it was a broom. The fear which came upon him was primitive, elemental. In some respects it was the kind of fear which a man in a dark wood would experience if he came upon a nest of copperheads while exploring a foliage-choked crevice in search of edible mushrooms. Expecting to find some poisonous varieties perhaps, but hardly death staring up at him out of the opaque eyes of a snake poised to strike. He moved slowly backwards, keeping the same distance from the entrance but putting as much space as possible between himself and the shuffling. He kept backing away until he came up against a firm metal barrier which he quickly explored with his hands. It had the solid feel of a wall. His breathing became a little less strained. With a wall at his back he was at least in no danger of being attacked from two directions. And if the wall made further retreat impossible the danger had not increased, for he was still the same distance from the entrance and could still, if he wished, make a very swift dash for it. He had no immediate intention of doing so. He stood listening, motionless and alert, his shoulders barely touching the wall. The shuffling sound did not seem to be coming any nearer. It even stopped for an instant. The silence closed in about him and he became aware of the over-loud beating of his heart. When the sound started up again it seemed to come from another direction, closer to the entrance. Now it _was_ nearer. Unmistakably louder and nearer, very close to him in the darkness. He strained his eyes, but could see nothing. He had to depend on his hearing alone, and hearing, he knew, could be deceptive. It was often very difficult to determine the precise location of a sound, to pinpoint it with any certainty. Suddenly his heart skipped a beat, and his breathing quickened. His throat turned cold as he swallowed, and tightened as well, the muscles stiffening, cording into knots. Unconsciously he gripped his leg, just above the knee, and dug his fingers into the flesh, as if physical pain alone could keep reality from taking on an aspect so nightmarish that his sanity would be imperiled.