“There’s nothing much to say about what I did in the house. I spent the time after Martin had left me in carefully thinking over the remaining steps in my plan, while I unloaded and thoroughly cleaned the revolver using my handkerchief and a penholder from the desk. I also placed the packets of notes, the note-case, and the diamonds in the roll-top desk, which I opened and relocked with Manderson’s key. When I went upstairs it was a trying moment, for though I was safe from the eyes of Martin, as he sat in his pantry, there was a faint possibility of somebody being about on the bedroom floor. I had sometimes found the French maid wandering about there when the other servants were in bed. Bunner, I knew, was a deep sleeper. Mrs. Manderson, I had gathered from things I had heard her say, was usually asleep by eleven; I had thought it possible that her gift of sleep had helped her to retain all her beauty and vitality in spite of a marriage which we all knew was an unhappy one. Still it was uneasy work mounting the stairs, and holding myself ready to retreat to the library again at the least sound from above. But nothing happened. “The first thing I did on reaching the corridor was to enter my room and put the revolver and cartridges back in the case. Then I turned off the light and went quietly into Manderson’s room. “What I had to do there you know. I had to take off the shoes and put them outside the door, leave Manderson’s jacket, waistcoat, trousers, and black tie, after taking everything out of the pockets, select a suit and tie and shoes for the body, and place the dental plate in the bowl, which I moved from the washing-stand to the bedside, leaving those ruinous finger-marks as I did so. The marks on the drawer must have been made when I shut it after taking out the tie. Then I had to lie down in the bed and tumble it. You know all about it—all except my state of mind, which you couldn’t imagine and I couldn’t describe. “The worst came when I had hardly begun my operations: the moment when Mrs Manderson spoke from the room where I supposed her asleep. I was prepared for it happening; it was a possibility; but I nearly lost my nerve all the same. However....