"Because I distinctly heard a movement in the hall about ten minutes ago," he answered. "Will you go round to the front and see if there are lights in any of the rooms, while I remain here? You'll soon see the house--the first with the long columns at the drawing-room windows." I consented, and was quickly round at the front. But the whole place was in total darkness. Not a light showed anywhere. I returned, and suggested that in passing he might have been mistaken. There were lights in the windows of the adjoining house. "No," declared the young man, who, by his speech, I recognised was well educated, "I made no mistake. There's some mystery here. I wired from Paris to Miss Greer this morning, making an appointment this evening. It's curious that she's out." "You are a friend of the family, I suppose?" I asked, eager to know who the young fellow was. "Yes," he replied; "and you?" "I am also," was my answer. What other reply could I make? "I believe the Professor is up in Scotland," I added. "But where is Antonio and all the other servants?" he argued. "Well," I said, "their master being absent, they may all be out, spending the evening; servants have a habit of doing so in the absence of their masters." "Then how do you account for the movements I have heard inside?" he asked. "No; if the servants are out, then the thieves are within. Will you stay here to bar their exit, while I go out and find a constable?" Mention of the police caused me to wince. This young man was in ignorance of what had really occurred. "I should remain patient a little while if I were you," I said. "Antonio may return at any moment; he surely cannot have gone far." "On the contrary, I think he has." "Why?" "Well, curiously enough, this afternoon, when I alighted from the Paris express and was passing through the buffet at Calais, I caught sight of a man who strangely resembled him. He turned his head and hurried away. At the moment I failed to recognise the likeness, and not until half an hour later, when the boat was already on its way across to Dover, did I recollect that he was very like the Professor's faithful Antonio." I held my breath. CHAPTER EIGHT. A FRESH TURN IN AFFAIRS. Here was the whole affair in danger of being exposed to the police and public by this young man's encounter with the Professor's servant! If it were exposed, then I should be compelled to give some account of myself. It would certainly be difficult to convince the police that I had no knowledge of the Professor's death. "Well," I remarked, "that Antonio should be leaving Calais seems somewhat curious, but perhaps it may have only been somebody resembling him." "Of course, I'm not quite sure," the young man replied; "but is it not curious that Miss Greer and the servants are all out? The Professor is always so very careful of his experiments and the contents of his laboratory that the house is never left untenanted."