At another time Carson might have dismissed the animal with a threatening gesture and returned to his work. But the traffic on Derby Street had been unusually noisy, and he had found it difficult to concentrate upon his novel. His nerves, for no apparent reason, were taut; and somehow it seemed that the rat, watching just beyond his reach, was eyeing him with sardonic amusement. Smiling at the conceit, he took a few steps toward the rat, and it rushed away to the cellar door, which he saw with surprize was ajar. He must have neglected to close it the last time he had been in the cellar, although he generally took care to keep the doors shut, for the ancient house was drafty. The rat waited in the doorway. Unreasonably annoyed, Carson hurried forward, sending the rat scurrying down the stairway. He switched on the cellar light and observed the rat in a corner. It watched him keenly out of glittering little eyes. As he descended the stairs he could not help feeling that he was acting like a fool. But his work had been tiring, and subconsciously he welcomed any interruption. He moved across the cellar to the rat, seeing with astonishment that the creature remained unmoving, staring at him. A strange feeling of uneasiness began to grow within him. The rat was acting abnormally, he felt; and the unwinking gaze of its cold shoe-button eyes was somehow disturbing. Then he laughed to himself, for the rat had suddenly whisked aside and disappeared into a little hole in the cellar wall. Idly he scratched a cross with his toe in the dirt before the burrow, deciding that he would set a trap there in the morning. * * * * * The rat’s snout and ragged whiskers protruded cautiously. It moved forward and then hesitated, drew back. Then the animal began to act in a singular and unaccountable manner—almost as though it were dancing, Carson thought. It moved tentatively forward, retreated again. It would give a little dart forward and be brought up short, then leap back hastily, as though—the simile flashed into Carson’s mind—a snake were coiled before the burrow, alert to prevent the rat’s escape. But there was nothing there save the little cross Carson had scratched in the dust. No doubt it was Carson himself who blocked the rat’s escape, for he was standing within a few feet of the burrow. He moved forward, and the animal hurriedly retreated out of sight. His interest piqued, Carson found a stick and poked it exploringly into the hole. As he did so his eye, close to the wall, detected something strange about the stone slab just above the rat burrow. A quick glance around its edge confirmed his suspicion. The slab was apparently movable.