For the moment he quite imagined that he was in his dormitory at school, and that by an oversight the rest of his chums had left him in bed. The suggestion was strengthened by the sound of gurgling water, as if the bathroom tap were running. Then he became aware that everything was pitching up and down. Once before he had experienced a similar sensation—when he had had a violent headache following a slight touch of sunstroke.

It puzzled him, too, that he was almost in darkness. Somewhere without, and partly screened by some projection, an electric light was burning. The reflected rays were just sufficient to enable him to take stock of his surroundings.

No, he was not back in the school dormitory. True, he had a headache, but that would not account for the actual motion. He fumbled, his fingers came in contact with a curved board that served to prevent the occupant of the bed—or, rather, bunk—from falling on the floor.

Almost mechanically he rolled out, and stood supporting himself by grasping the ledge of the bunk. The swaying, due partly to dizziness and partly to an unaccountable see-saw motion, would have thrown him to the floor but for the assistance afforded by the side of the bunk.

Gradually he became aware that there was a similar sleeping-place immediately beneath the one he had been occupying. Someone was lying there, breathing heavily. There was sufficient light for Ross to recognize him. It was his chum Vernon.

Just then a bell clanged noisily. The sound of running water was outvoiced by the loud din of machinery in motion. A wave of hot air that reminded the lad of the atmosphere of a Tube station wafted past him. The whole fabric trembled under the powerful pulsations of the mechanism.

With his legs trembling through sheer physical weakness, Ross hung on grimly. He wanted to shout, but no sound came from his parched tongue. He was bewildered. It seemed as if he were in the throes of a terrible nightmare, and that he would awake on finding himself falling into a bottomless abyss.

The reflected light was obscured as a broad-shouldered man made his way along the narrow corridor in which the bunks were placed. As he did so he caught sight of the lad. Without a word he seized Ross in his arms, not roughly, but nevertheless unceremoniously, and lifted him back into the bunk. There was something so peremptory in the action that Ross lay still and closed his eyes. All his will power seemed to have deserted him.

"Make a dash for it, old man!" exclaimed a muffled voice that Trefusis hardly recognized as his chum's. "Make a dash for it. Don't let them collar us."

It was Vernon rambling in his sleep. The words were sufficient to give Ross a key to the hitherto baffling problem.