Crossing a hall that is a marvel of antique richness, with its walls of russet, old gold, and Venetian red tints; its big claw-footed tables; its massive, open-faced clock, with huge weights a-swing below; its statuettes and its bass-reliefs, we pass under a rich _portierie_, and hear the liveried footman say, evidently having been instructed: "This is Mr. Warburton's study, sir; I will take up your name." Van Vernet gazes about him, marking the gorgeous richness of the room. A study! There are massive book-cases filled with choicest lore; cabinets containing all that is curious, antique, rare, beautiful, and costly; there are plaques and bronzes; there is a mantle laden with costly bric-a-brac; a grand old-fashioned fire-place and fender; there are divans and easy chairs; rich draperies on wall and at windows, and all in the rarest tints of olive, crimson, and bronze. Van Vernet looks about him and says to himself: "This is a room after my own heart. Mr. Warburton, of Warburton Place, must be a sybarite, and should be a happy man. Ah, he is coming." But it is not Mr. Warburton who enters. It is a colored valet, sleek, smiling, obsequious, who bears in his hand a gilded salver, with a letter upon it, and upon his arm a parcel wrapped in black silk. "You are Mr. Vernet?" queries this personage, as if in doubt. "Yes." "Then this letter is for you." And the valet bows low, and extends the salver, adding softly: "I am Mr. Warburton's body servant." Looking somewhat surprised, as well as annoyed, Van Vernet takes up the letter, breaks the seal and reads: SIR: My business with you is of so delicate a nature that it is best, for all concerned, to keep our identity a secret, for a time at least. Your investigation involves the fair fame of a lady and the honor of a stainless name. Come to this house to-morrow night, in the costume which I shall send for your use. The enclosed card will admit you. My valet will show you the domino by which you will recognize me. This will enable me to instruct you fully, and to point out to you the persons in whom you are to take an interest. This letter you will please destroy in the presence of my valet. A. W. After reading this strange note, Van Vernet stands so long, silently pondering, that the servant makes a restless movement. Then the detective says, with a touch of imperiousness. "Give me a match." It is proffered him in silence, and in silence he turns to the grate, applies the match to the letter, and lets it fall from his fingers to the fire-place, where it lies a charred fragment that crumbles to ashes at a touch. The dark servant watches the proceeding in grave silence until Vernet turns to him, saying: "Now, the domino." Then he rapidly takes from the sable wrapper a domino of black and scarlet, and exhibits it to the detective, who examines it critically for a moment and then says brusquely: