"But it ought to have, for of all the theories we have as yet entertained, this one is by far the most probable. You see," he continued, "you allow your judgment to be warped by your unwillingness to associate the young lady, even indirectly, with a crime." "Perhaps so," I acknowledged. "Now, I must tell you that, however innocent Miss Derwent may eventually prove to be, since my last talk with you I have become convinced that the murder was committed in her parlour, and nowhere else." Mr. Merritt spoke very earnestly, leaning across the table to watch the effect on me of what he was saying. "Ah," I exclaimed angrily, "then you deceived me----" "Gently, gently, young man; I don't deceive anybody. I told you that I wished the young lady well; so I do--that I believed in her innocence; I still do so. I said that the information I had received from you materially helped her case, which it most assuredly did. Had you withheld certain facts it would have been my duty--my painful duty, I acknowledge--to have arrested Miss Derwent last Saturday." "But why?" I inquired. "Because all the evidence pointed towards her, and because my belief in her innocence rested on no more solid foundation than what is called intuition, and intuition is a quicksand to build upon." "But what was there to point to her except that a negro boy thought that the dead man resembled Greywood?" "Ah, you acknowledge that her visitor was Mr. Greywood?" "Yes, I grant you that, but what of it? I am convinced he has not been murdered." "But why?" demanded the detective. "Now, listen to this. The body is identified by two people as Greywood's. Greywood disappears at about the same time that the crime was committed. We know that the corpse must have been hidden somewhere in the Rosemere for twenty-four hours. Where could it have been more easily secreted than in the Derwents' apartment, into which no outsider or servant entered? And lastly, it would have required two people to carry, even for a short distance, a body of its size and weight; but as the young lady was not alone, but had with her the man and woman whom you saw, this difficulty is also disposed of. From all this, I conclude that the Derwents' flat was the scene of the tragedy." "But why should Greywood have been killed?" I asked. "What possible motive could there have been?"