"Isn't that a queer move for His Dignity?" "Well, I don't know. Presuming the fair Mystery to be an intruder, he may think it the easiest way of putting her to rout. At any rate there's a little spice in it." And there is spice in it. Before the evening closes, the festive Celestial is willing to vote this meeting with a veiled mystery an occasion full of flavor, and worthy to be remembered. Leaving the pair in full chase after the luckless, petticoat-encumbered Stanhope, we follow Van Vernet, who, having set this trap for the feet of his unconscious comrade, is about to play his next card. Gliding among the maskers, he makes his way to a side entrance, and passing the liveried servant on guard at the door with a careless jest, he leaves the house, and hastens where, a few rods distant, a solitary figure is standing. "How long have you been here, Harvey?" he asks hurriedly, but with noticeable affability. "About half an hour." "Good; now listen, for you are to begin your business. Throw on that domino and follow me; the servants have seen me in conversation with the master of the house and they will not require your credentials. Keep near me, and follow me to the dressing-rooms; by-and-by we will exchange costumes there, after which, you will personate me." "But,--" "There will be no trouble; just mingle with the throng, saying nothing to anyone. No one will address you who could doubt your identity; I will arrange all that. You comprehend?" "I think so. You are wanted, or you want to be, in two places at once. This being the least important, you place me here as figure-head, while you fill the bill at the other place." "You have grasped the situation, Harvey. Let us go in, and be sure you do justice, in my stead, to the banquet--and the Warburton champagne." Van Vernet had planned well. Knowing the importance of the Raid in hand for that night, he had determined to be present and share with Stanhope the honors of the occasion, while he seemed to be devoting all his energies to the solution of the mystery that was evidently troubling his wealthy patron, the master of Warburton Place. Vernet was a man of many resources, and trying, indeed, must be the situation which his fertile brain could not master. Having successfully introduced his double into the house, he made his way, once more, to the side of his patron, and, drawing him away from the vicinity of possible listeners, said: "Mr. Warburton, if you have anything further to say to me, please make use of the present moment. After this it will be best for us to hold no further conversation to-night." Alan Warburton turned his eyes toward the detective with a cold, scrutinizing stare. "Why such caution?" "Because it seems to me necessary; and, if I may be permitted to suggest, you may make some slight discoveries by keeping an eye, more or less, upon Mrs. Warburton."