The waiter hurried away, and Harley stood glancing up the stairs as if in doubt what to do. “I cannot imagine how such a place can pay,” he muttered. “The rent must be enormous in this district.” But even before he ceased speaking I became aware of an excited conversation which was taking place in some apartment above. “It's scandalous!” I heard, in a woman's shrill voice. “You have no right to keep it! It's not your property, and I'm here to demand that you give it up.” A man's voice replied in voluble broken English, but I could only distinguish a word here and there. I saw that Harley was interested, for catching my questioning glance, he raised his finger to his lips enjoining me to be silent. “Oh, that's the game, is it?” continued the female voice. “Of course you know it's blackmail?” A flow of unintelligible words answered this speech, then: “I shall come back with someone,” cried the invisible woman, “who will make you give it up!” “Knox,” whispered Harley in my ear, “when that woman comes down, follow her! I'm afraid you will bungle the business, and I would not ask you to attempt it if big things were not at stake. Return here; I shall wait.” As a matter of fact, his sudden request had positively astounded me, but ere I had time for any reply a door suddenly banged open above and a respectable-looking woman, who might have been some kind of upper servant, came quickly down the stairs. An expression of intense indignation rested upon her face, and without seeming to notice our presence she brushed past us and went out into the street. “Off you go, Knox!” said Harley. Seeing myself committed to an unpleasant business, I slipped out of the doorway and detected the woman five or six yards away hurrying in the direction of Piccadilly. I had no difficulty in following her, for she was evidently unsuspicious of my presence, and when presently she mounted a westward-bound 'bus I did likewise, but while she got inside I went on top, and occupied a seat on the near side whence I could observe anyone leaving the vehicle. If I had not known Paul Harley so well I should have counted the whole business a ridiculous farce, but recognizing that something underlay these seemingly trivial and disconnected episodes, I lighted a cigarette and resigned myself to circumstance. At Hyde Park Corner I saw the woman descending, and when presently she walked up Hamilton Place I was not far behind her. At the door of an imposing mansion she stopped, and in response to a ring of the bell the door was opened by a footman, and the woman hurried in. Evidently she was an inmate of the establishment; and conceiving that my duty was done when I had noted the number of the house, I retraced my steps to the corner; and, hailing a taxicab, returned to the Cafe Dame. On inquiring of the same waiter whom Harley had accosted whether my friend was there: “I think a gentleman is upstairs with Mr. Meyer,” said the man. “In his office?” “Yes, sir.”