Hanslet, who had been silent for a moment or two, suddenly turned towards Whyland. “You say that nobody came near you while you were alone here but young Copperdock. What did he want, I wonder? Have you seen him since you came back from your herbalizing expedition, Mr. Ludgrove?” A grave expression spread over the herbalist’s face. “I have,” he replied. “It was for this reason that I asked Inspector Whyland to come here and see me. I was about to tell him the story when you came in, and I realized that it would be better if you heard it together. Ted Copperdock came here yesterday evening, about an hour after my return.” “Oh, he did, did he!” exclaimed Hanslet. “What did he want?” “He told me he had come round in the morning to ask me if I would go through his father’s belongings with him. Finding me busy, as he supposed, he went back home, and started to go through them by himself. He spent the whole afternoon sorting out Mr. Copperdock’s papers, and it was not until late that he began to look over his clothes. In the pocket of one of his coats he discovered something which, as he himself said, terrified him. He came to me at once, and begged me to come back with him. He was so insistent that I broke the promise which I had made to Inspector Whyland, not to go alone into any house in Praed Street, and went upstairs with him into his father’s bedroom. There he showed me an overcoat hanging in a cupboard, and in the pocket of it—this!” The herbalist rose, walked to the bench at the far end of the room, and pointed to an object wrapped loosely in paper. Hanslet and Whyland followed him, and the former unwrapped the paper carefully. As the object appeared, they both uttered a startled exclamation. It was the blade of a knife, and with it a long wooden handle, with a hole running the whole of its length, and fitted with a set-screw. Whyland bent over it with a look of triumph. “I knew it, all along!” he exclaimed. “Look at this blade! It is exactly similar to the ones found in the bodies of Tovey and Pargent. You see the dodge, don’t you? This blade just fits the hole in the handle. It’s meant to be pushed through and gripped by the set-screw. But, if you tighten the screw as far as it will go first, then put the blade in, it is held lightly, just by its very end. Now, if you stab a man with the blade fixed like that, what happens? The blade goes in all right, and there it stays, while you walk away with the handle. It’s beautifully simple, and you leave no finger-marks behind you.”