"I pointed that out to you at the time," remarked the Italian doctor with a sigh. "But what you have just shown to me is amazing. I never dreamed of that!" He had evidently shown him something in the moonlight. "Well, I don't intend that this fellow shall pry into my affairs," snapped the millionaire. I recognized that hard metallic voice of his, and it recalled to me all those strange happenings on that November night. "I do not really see, if we act boldly, what we have to fear," said the doctor in his very fair English. We! Then they were both implicated in the plot, whatever its nature. "Fear!" echoed De Gex. "Suppose he made some very compromising statement to the London police." "And in doing so he would compromise himself! He posed as a medical man, and gave the death certificate in return for payment--five thousand pounds. Beyond, he committed forgery by signing the name of Gordon Garfield. No, Mr. De Gex, I feel sure he will never court prosecution. He may busy himself in trying to solve what no doubt appears to him a complete enigma--as indeed it is to us. But he will never expose us--_never_!" The millionaire grunted dubiously. "Well, what are we to do now? What do you suggest, Moroni? Your brain is always so fertile where crooked business is concerned." "I have no suggestion. I came here to learn yours." "Yes. I called you here to show you what I have shown you, and also because I have a certain person here as guest at my wife's dance to-night--you know whom I mean." "Certainly. She is equally dangerous. You asked me to bring the little tube. Here it is. But I urge you to use it with extreme caution. When you break the glass be certain that none of the jelly inside touches your fingers. If it does, wash them instantly in carbolic. It is highly contagious." De Gex gave vent to a queer laugh of satisfaction, as, no doubt, he took the mysterious glass tube in his hand. "I am not yet certain whether to try the experiment--or not," he remarked with hesitation. "It is, to say the least, a highly dangerous one." "You mean dangerous from the point of view of discovery--eh?" "No, not at all. Your act cannot be discovered, but it may be dangerous for yourself and those about you--highly dangerous. I have obeyed your orders, signore, as I always do, and I have brought it. But my suggestion is that you should not break that tube and disperse its contents." "You seem to be growing unusually apprehensive, my dear Moroni. The appearance in Florence of this young electrical engineer seems to have quite upset you!" he laughed harshly. I could hear every word. "I confess his presence here has not inspired me with confidence. We do not know the extent of his knowledge, or what he has discovered," replied the doctor. "If he establishes one fact--you know to what I refer--then he will become a very grave menace to us both."