The hissing sound stopped. Instead, under a pressure of nearly two and a half atmospheres, the water rushed into the disconnected valve. In five seconds it had risen to the sub’s knees. Then the inrush was checked. It was useless to struggle, but with an uncontrollable longing to wrench himself away from his captors, rather than be drowned like a rat, Hythe persisted in his efforts, till he realized that he was in no immediate danger of being suffocated. In the place of the air pumped in from above--air that was anything but fresh--came a cool, invigorating vapour strongly charged with oxygen. He no longer appealed for aid. He knew that with the air-tube and life-line the telephone wire had been severed. He was cut off from all intercourse from above. Even his air supply was self-contained. Instinctively he felt certain that he would be carried off to the mysterious submarine. Curiosity prompted him to accept the situation with equanimity, his inborn fighting disposition urged him to resist. If he were to be made a prisoner he would let his captors know that the liberty of a British officer is not lightly lost. It was a strange procession on the sandy floor of Cawsand Bay, for others of the submarine’s crew had come upon the scene, and surrounded and held by five weirdly-garbed and helmeted men Hythe was frog-marched towards the huge submerged vessel. A dull patch in the side of the craft indicated that a portion of her plating had been swung back, revealing on closer inspection a door about five feet in height and thirty inches wide. Here the sub saw his chance. With outstretched arms and legs he defied the crowd of captors to pass his resisting body through the narrow aperture. Twice he almost freed himself from their clutches. The oxygen-charged vapour he was breathing accentuated his fighting instincts, and mainly through sheer delight at being able to thwart his antagonists he lashed out right and left. Still retaining their hold the men began to lose patience. One of them turned and looked at another who was standing by. The look was understood. Drawing a small instrument resembling a two-pronged fork, from a sheath attached to his belt, the fellow advanced towards the young officer. Hythe, still resisting, saw the action. "I wonder what he’s up to?" he muttered. "Going to puncture my suit, I suppose, and half-drown me. Take that, you under-handed rascal." With a sudden wrench he freed his right hand, and clenching his fist hit madly at the diver’s front plate. Had the blow struck home the glass would in all probability have been broken, but the man stepped backwards and the sub’s fist encountered water only. That attempt led to Hythe’s undoing, for two stalwart fellows seized him by the arm of his india-rubber suit between wrist and elbow. Held as in a vice he was unable to draw back his hand, the diver with the fork-like instrument immediately applied the points to the officer’s bare knuckles.