“He changed into Robert’s clothes in the office bedroom. This was the safest way—for both of us. When he was ready, he called me in, and I inspected him. It was extraordinary how well he looked the part. I suppose that the signs of his dissipation had already marked themselves on his face, but had been concealed hitherto by his moustache and beard; for now that he was clean-shaven they lay open to the world from which we had so carefully hidden them, and he was indeed the wastrel which he was pretending to be. “‘By Jove, you’re wonderful,’ I said. “He smirked, and called my attention to the various artistic touches which I might have missed. “‘Wonderful,’ I said to myself again. ‘Nobody could possibly guess.’ “I peered into the hall. It was empty. We hurried across to the library; he got into the passage and made off. I went back to the bedroom, collected all his discarded clothes, did them up in a bundle and returned with them to the passage. Then I sat down in the hall and waited. “You heard the evidence of Stevens, the maid. As soon as she was on her way to the Temple in search of Mark, I stepped into the office. My hand was in my side-pocket, and in my hand was the revolver. “He began at once in his character of Robert—some rigmarole about working his passage over from Australia; a little private performance for my edification. Then in his natural voice, gloating over his well-planned retaliation on Miss Norris, he burst out, ‘It’s my turn now. You wait.’ It was this which Elsie heard. She had no business to be there and she might have ruined everything, but as it turned out it was the luckiest thing which could have happened. For it was the one piece of evidence which I wanted; evidence, other than my own, that Mark and Robert were in the room together. “I said nothing. I was not going to take the risk of being heard to speak in that room. I just smiled at the poor little fool, and took out my revolver, and shot him. Then I went back into the library and waited—just as I said in my evidence. “Can you imagine, Mr. Gillingham, the shock which your sudden appearance gave me? Can you imagine the feelings of a ‘murderer’ who has (as he thinks) planned for every possibility, and is then confronted suddenly with an utterly new problem? What difference would your coming make? I didn’t know. Perhaps none; perhaps all. And I had forgotten to open the window!