Perhaps some one saw him, but he had put on an air of proprietorship such as Joe wore, and curious eyes must have simply reached the conclusion that his coming was but another link in the chain of mystery surrounding the house. Once in the hall, the detective quietly closed the door, making sure it was fast. Enough light came in through the glass above to show him the stairs. There was carpet on the floor. Near by were folding doors, and, as they stood ajar, Darrell poked his head through, not merely out of curiosity, but because he felt that he had an interest in the matter. The parlor was furnished. It was no empty house into which he had come thus surreptitiously. He listened. Not a sound from within. How strange it seemed. What could it all mean? Vague and even terrible ideas flashed into his mind—was Joe connected with some secret cabal or society that met here every day? Perhaps some awful secret was gnawing at his vitals, and daily sapping his life. What was that? A door slammed above. Eric was glad to hear it, for he realized that the house had something human about it. As near as he could judge the sound came from upstairs. Then he would not have to grapple with the demons of the underground world. At times even the oddest fancies will surge through the most prosaic mind. One of the thoughts that had come to him was that possibly Joe had become connected with some gang of counterfeiters—he had heard of things just as strange—and although it seemed a preposterous idea in connection with Joe, still it had already become apparent that there was something very strange connected with him and why not this as well as any other? Lately Eric had been reading Doctor Jekyll and Mr. Hyde, and his mind was full of strange fancies concerning the awful change that was wont to come over that unfortunate being, who lived two lives, each unknown to the other. It did not seem possible that Joe Leslie could be doing this exactly, but he might be carrying on two characters successfully. At his business and his home up-town he was known as Joseph G. Leslie—on Twenty-seventh Street he might be Mr. Lester. To tear the mask away and expose the truth was what brought the detective here now. In the interest of justice he was bound to do this much. Then again he thought of Lillian. In his indignation he wished she could be there to face her husband when his guilty secret was laid bare. It might seem cruel—so does the hot iron of the doctor when applied to the marks left by the teeth of an enraged dog, but it is done with kindness—heroic treatment saves one from something more terrible beyond. Perhaps, if faced by Lillian, Joe would break down and receive a shock that would last him all the rest of his natural life. So the detective made up his mind not to betray his presence now if he could help it, but reserve the _denouement_ to a later date, when it could be made more dramatic.