“They did as I told them, pulled back the two heavy black curtains that were in front of the window. It was set back in a sort of alcove, and I had the revolver ready pointed to cover the murderer. I covered empty air; there was no one there. Then I walked over to the window and looked out. It was wide open, and there was a sheer drop of forty feet to the deserted area below. I looked upwards—I looked sideways: plain brickwork without footing for a cat.” “‘Go down to the room below,’ I cried; ‘he may have got in there.’ “They rushed away to come back and tell me that not only were the windows bolted, but that they were shuttered as well. And I thought they looked at me curiously.” He paused to relight his cigar; then he continued thoughtfully: “I don’t quite know when I first began to feel suspicious about this mysterious man. The thing had been so sudden that for a while my brain refused to work; then gradually my legal training reasserted itself, and I started to piece things together. Ruth had come-to again, and I put one or two questions to her. She was still very dazed, but she answered them quite coherently: “A man in evening clothes—at least, she thought he had on evening clothes—had been in the room as she came in. She heard a shot; the light went out and the window was thrown up. And then she had turned on the light just before I came in to see her husband lying dead on the floor. She knew no more. I suppose I must have looked a bit thoughtful, for she suddenly got up from her chair and came up to me. “‘You believe me, Bill, don’t you?’ she said, staring at me. “‘Of course, of course,’ I answered hurriedly. ‘Go and lie down now, Ruth, because we shall have to send for the police.’ “Without another word she left the room with her maid, and, after telling the footmen to wait downstairs till they were wanted, I sat down to think. Now, this isn’t a detective story; such as it is, it concerns a more interesting study than the mere detection of crime. It concerns the struggle in the soul of an upright man between love and duty. And the man was Sir Edward Shoreham. “Unknown to me she sent for him—asked him to come at once—and he came. He was shown by the butler into the study, where I was still sitting at the desk, and he stopped motionless by the door staring at the body, which had not been moved. I was waiting for the doctor, and I got up surprised. “‘The butler told me he had been shot,’ he said a little jerkily. ‘How did it happen?’ “‘I wasn’t expecting you, Sir Edward,’ I answered slowly. ‘But I’m glad that you’ve come. I’d like another opinion.’ “‘What do you mean?’ he cried. ‘Is there any mystery?’