"Now, I was sure that the grocery and its proprietor, the two pounds of the best butter, and the purple trading-stamp had nothing to do with the real business of the evening. The game was simply to identify the 'Mr. House-smith' who had advertised for his ninety-and-nine kisses, and the clap-trap of the message in telegraphic characters, and all the rest of it, were simply the kind of bait at which so eccentric a person might be expected to bite. The gentleman with one ear larger than the other desired to find the elusive Mademoiselle D., erstwhile dispenser of kisses at an East Side charity bazaar, and, consequently, he was following up every possible clew. He wanted 'Mr. House-smith,' and I wanted him. "Fight shadows with shadows, remember; and so I took service with my honest friend, David Brown, dealer in groceries at West Fourth and Eleventh streets. He was rather offish at first, but Mattson, at Police Head-quarters, had provided me with a special detective badge, and Mr Brown was led to believe that I was working up a case of graft. He lent me a jumper, and I was forthwith installed behind the counter. "Everything went off according to schedule. The 'shadow' had his cab in readiness and I had mine. He trailed you to No. 4020 Madison Avenue, and I followed Mr. Shadow to the Central Detective Office. It seems to have been a case of sleuth against sleuth, with the match all square." "Anything else?" "Well, yes. As I came into the house just now, two men were waiting for me in the vestibule. They went through me; but I didn't seem to have what they wanted. I still retain possession of my watch and purse." "So," I said, somewhat helplessly. "What's the next move on the board?" "It is the last night of the supplementary opera season," answered Indiman, "and we are going to dress and see what we can of Tschaikowsky's 'Queen of Spades.' A novelty--first and only performance outside of Russia, and Ternina heads the cast." "There is Mademoiselle D.," remarked Indiman, as his glass swept the semicircle of the parterre. "The fourth box from the end." There were but three people in the party--the girl with the gray eyes, an elderly man with a ribbon in his button-hole, and Jack Crawfurd, whom everybody knows. The curtain fell on the third act, and immediately Crawfurd made his appearance in the omnibus-box where we were sitting. "Come with me, mes enfants," he said, genially. "It seems that you and the adorable Countess Gilda are old friends. She commands your instant attendance. What, man! do you hesitate? I shall lose my head an our sovereign lady be not instantly obeyed." The girl with the gray eyes greeted us with smiling unconcern. "Do you know my uncle?" she asked, and we were forthwith presented to his Excellency Baron Cassilis, the Russian ambassador to the United States. Then the Countess Gilda addressed herself squarely to Indiman.