Again eternity passed: the door was still shut. He wasn’t coming; the acting had been in vain. Hubert Garling had seen, as he thought, their agony before they became unconscious; now he was going to make quite certain they were dead before he bothered with them further. And with a dreadful feeling of physical sickness Jack Denver realized that, though the acting had been in vain, it had been a wonderful dress-rehearsal. Even so, in reality, would Hilda pitch forward and lie still; even so would he tear at his collar and fight for the air which was not there. The girl had risen, and he rose too, and went to her. “He’s not coming, Jack,” she said, steadily. “We’ve failed.” “Yes, dear—I’m afraid we’ve failed.” “So this is the end.” He made no answer; only put his arm round her waist and held her tightly. “I’m not frightened, my man,” she went on, quietly. “I expect I’ll go first, but you’ll find me waiting for you over the other side of the valley.” He cried aloud in his agony of mind; already he felt as if an iron band was pressing round his head. “Oh, God!—if I could only get a message through somehow.” And even as his prayer went up, his eyes rested on the electric light switch. He’d seen it fifty times before; he’d used it in that last despairing throw for safety; and now—he stared at it as if he’d seen it for the first time. Fool that he was—idiot, not to have thought of it before. The tower could be seen from the road, even if he couldn’t be heard from there. And it was the only chance. He turned off the light; then he began to signal. Three short bursts of light; three long ones; three short again. S.O.S. Then HELP in Morse. Again and again S.O.S. HELP. S.O.S. HELP. And the iron band round his head grew tighter and tighter. How long he went on he had no idea; time was measured only by the click of the switch—on and off. Dimly he realized that the girl had got to her feet, and with a dreadful look in her face was staggering towards him. He felt her clutch hold of his arm; from a great distance he heard her voice: “Jack—I can’t breathe; I can’t——” Her grip relaxed, and she collapsed on the floor at his feet, struggling horribly to breathe. S.O.S. HELP. S.O.S. HELP. Slower and slower the message flashed out into the night, until, at last, it ceased altogether. And Jack Denver’s knees gave from under him. With one last effort he turned off the light; then he crumpled up on the floor beside the woman he loved. And so they found them—two naval officers, one of whom, by the mercy of Allah, was a doctor. “My God!” he gasped, as they flung open the door and the atmosphere inside hit them. “Get ’em into the fresh air, Flags; and for Heaven’s sake—hurry.” “Are they dead, Doc?” cried his companion, as they laid the two unconscious bodies by an open window. “No—but damned near it.” He looked thoughtfully at his brother officer. “Go down and see what’s happened to that madman below, old boy. I’ll look after these two.”