She had lost a valuable diamond-studded watch, and when the most careful search failed to discover it, the conclusion arrived at was that some thief must have been present at the reception. It was an unpleasant conclusion to arrive at. But it was the only natural one. For the Ambassador’s wife had not left her guests, or gone beyond the reception rooms, from the time she entered them, wearing the watch, to the moment when, the last visitors having just gone, she thought of looking at her watch, and found that it had disappeared. Mrs Bevan’s return a few moments later with the news that her pendant had disappeared, confirmed the supposition that some professional thief must have been at work, and the police were at once communicated with. They were also strictly enjoined to keep the matter a profound secret, for various reasons. But Mrs Bevan was too anxious to rely entirely upon the exertions of the regular force, hence her application to our firm and her urgent entreaty that I would act with the utmost despatch. Soon after my client’s departure I sought an interview with Madame von Auerbach, but could glean very little useful information. The invitations had been sent out with great care, but their exclusiveness was negatived by the fact that they were all sent to So-and-so and friend. The position of those invited by name had been considered sufficient guarantee of the perfect suitability of the friends whom they might select to accompany them to the embassy, and at least a score of people had been present of whom the hostess barely heard even their names. Of course, no one could treat any single one of these individuals as suspects without some definite suspicion to work upon, and unfortunately for our prospects of success, there was not the slightest ground for suspecting anyone in particular. I was about to quit Madame von Auerbach’s house when a servant entered with a card upon a waiter, and upon hearing that the name inscribed thereon was that of one of the guests of the previous evening, I hastily decided to stay a little longer, and requested Madame von Auerbach to keep my vocation a secret from her visitor. The next minute a most bewitching little woman was ushered into the room. “Oh, my dear madame!” she exclaimed, with a charming foreign accent. “Such an unfortunate thing! I lost my beautiful diamond clasp last night. Have your servants seen anything of it?” Madame von Auerbach turned pale, and I looked with augmented interest at the harbinger of this new development of the previous evening’s mystery. The depredations had evidently been on a large scale, and the depredators had shown remarkably good taste in the choice of their spoil. The latest victim was a French lady named Madame Duchesne, and she waxed eloquent in lamentations over her loss when it was shown to her how little hope there was of recovering her diamond clasp.