"Why, certainly," said McMurtrie, smiling. "There is no mystery about it. I was merely keeping the matter quiet until it was settled." He turned to me. "The German Government have made us a very good offer for your invention, provided of course that it will do what you claim." "It will do what I claim all right," I said coolly, "but I don't wish to sell it to the German Government." There was a sort of explosive gasp from von Brünig and Savaroff, and I saw McMurtrie's eyes narrow into two dangerous cat-like slits. "_You don't-wish!_" he repeated icily. "May I ask why?" "Certainly," I said. "With the sole command of an explosive as powerful as mine, Germany would be in a position to smash England in about six weeks." "And suppose she was," interrupted von Brünig. "What in God's name does it matter to you--an escaped convict?" His voice rang with impatience and contempt, and I felt my own temper rising. "It matters just sufficiently," I said, "that I'll see you in hell first." McMurtrie came slowly up to me, and looked me straight in the eyes. His face was white and terrible--a livid mask of controlled anger. "You fool," he said almost pityingly. "You incredible fool! Do you imagine that you have any choice in the matter?" Von Brünig and Savaroff moved up alongside of him, and I stood there confronting the three of them. "You have heard my choice," I said. McMurtrie laughed. It was precisely the way in which I should imagine the devil laughs on the rare occasions when he is still amused. "You are evidently a bad judge of character, Mr. Lyndon," he said. "People who attempt to break faith with me are apt to find it a very unhealthy occupation." I felt utterly reckless now. I had done my best to delay things, and if neither the police nor the Secret Service was ready to take advantage of it, so much the worse for them--and me. "I can quite believe you, doctor," I said pleasantly. "I should imagine you were a dangerous ruffian from the intelligent way in which you murdered Marks." It was a last desperate stroke, but it went home with startling effect. Savaroff's face flushed purple, and with a fierce oath he gripped the back of a chair and swung it up over his head. The doctor stopped him with a gesture of his hand. As for von Brünig, he stood where he was, staring from one to the other of us in angry bewilderment. He evidently hadn't the remotest notion what I was talking about. McMurtrie was the first to speak. "Yes," he said, in his coolest, silkiest voice. "I did kill Marks. He was the last person who betrayed me. I rather think you will envy him before I have finished with you, Mr. Lyndon." "A thousand devils!" cried von Brünig furiously: "what does all this nonsense mean? We may have the police here any moment. Knock him on the head, the fool, and--" "Stop!"