I responded to this confidential communication with due sympathy, and gravely acknowledged the attention my new companion bestowed upon me for a few moments. And I had need of my gravity and presence of mind. For the man introduced to me was not my uncle, the detective. I knew that our firm had not been applied to by Madame Duchesne, in spite of her assertion to the contrary, and as this was certainly no one who had ever been in our office, I knew that certain suspicions that I had formed yesterday were likely to be verified. Since this stranger was certainly no detective, I concluded that he was merely posing as one for the sake of diverting suspicion from the offenders whom I was anxious to run to earth. The assumption that he was the associate and helpmate of the thieves was also a very natural one, although a glance at the lovely hostess and her dainty surroundings almost seemed to belie such a supposition. But I knew that I was on the right track, and within the hour my vigilance was rewarded. The sham detective, whose pretended avocation had been disclosed to none but Madame von Auerbach and myself, sauntered from group to group, as if intent upon scrutinising their actions. His real object was to attach their jewellery, and I had the satisfaction of seeing him possess himself of a costly watch which Lady A. was wearing in somewhat careless fashion. Instant denunciation was not my intention. I mean to probe the matter to the root, and followed “Mr Bell’s” movements with apparent nonchalance. Presently he culled a couple of beautiful standard roses, and handed them to Madame Duchesne with a graceful compliment. The thing was beautifully done, and none but a person keenly on guard would have noticed that the watch changed hands with the roses. This little comedy over, Madame sauntered towards the house, and, five minutes later, I came upon her, quite by accident, of course, just as she was relocking a dainty cabinet from which she had taken a fresh bottle of perfume, in the use of which she was very lavish. There were two or three other people in Madame’s charming boudoir, among them being Madame von Auerbach, by whose side I seated myself with an air of sudden weakness. She was really startled by the development of events, but she had been previously cautioned, and played her part very well indeed, when I exclaimed that I felt dreadfully ill. “What shall I do?” she cried. “I hope it is not one of your old attacks.” “Yes, it is,” I whispered faintly. “Do send for my uncle. He is the only one who can help me.” I was promptly placed on the couch, and dosed with all sorts of amateur remedies, pending the arrival of my uncle, who had been sent for in hot haste, and who, “entre nous,” was waiting with a police officer in private clothes for the expected urgent summons. No sooner did they appear than my indisposition vanished, and I astonished the bystanders by springing vigorously to my feet.