I had no plan. Nevertheless, I walked boldly upstairs. There was but one flat on each floor. At the third story I halted, rather out of breath, in front of a door with a small brass plate inscribed with the name "Eugen Kore." I rang the bell boldly. An elderly man-servant opened the door. "Is Herr Eugen Kore at home?" I asked. The man looked at me suspiciously. "Has the gentleman an appointment?" he said. "No," I replied. "Then the Herr will not receive the gentleman," came the answer, and the man made as though to close the door. I had an inspiration. "A moment!" I cried, and I added the word "Achilles" in a low voice. The servant opened the door wide to me. "Why didn't you say that at once?" he said. "Please step in. I will see if the Herr can receive you." He led the way through a hall into a sitting-room and left me there. The place was a perfect museum of art treasures, old Dutch and Italian masters on the walls, some splendid Florentine chests, a fine old dresser loaded with ancient pewter. On a mantelshelf was an extraordinary collection of old keys, each with its label. "Key of the fortress of Spandau, 1715." "Key of the Postern Gate of the Pasha's Palace at Belgrade, 1810," "House Key from Nuremberg, 1567," were some of the descriptions I read. Then a voice behind me said: "Ah! you admire my little treasures!" Turning, I saw a short, stout man, of a marked Jewish appearance, with a bald head, a fat nose, little beady eyes and a large waist. "Eugen Kore!" he introduced himself with a bow. "Meyer!" I replied, in the German fashion. "And what can we do for Herr ... Meyer?" he asked in oily tones, pausing just long enough before he pronounced the name I gave to let me see that he believed it to be a pseudonym. "I believe you know a friend of mine, whose address I am anxious to find," I said. "Ah!" sighed the little Jew, "a man of affairs like myself meets so many people that he may be pardoned.... What did you say his name was, this friend of yours?" I thought I would try the effect of the name "Eichenholz" upon this enigmatic creature. "Eichenholz? Eichenholz?" Kore repeated. "I seem to know the name ... it seems familiar ... now let me see again.... Eichenholz, Eichenholz. ..." While he was speaking he unlocked one of the oak cabinets and a safe came to view. Opening this, he brought out a ledger and ran his finger down the names. Then he shut the book, replaced it, locked the safe and the cabinet, and turned to me again. "Yes," he said, "I know the name." His reticence was disconcerting. "Can you tell me where I can find him?" I asked. "Yes," was the reply. I was getting a trifle nettled. "Well, where?" I queried.