“I never thought of that,” I said slowly.
“Let us, dear Mr. Clement, just go over it again. Mrs. Protheroe comes to the window and she thinks the room is empty—she must have thought so, because otherwise she would never have gone down to the studio to meet Mr. Redding. It wouldn’t have been safe. The room must have been absolutely silent if she thought it was empty. And that leaves us three alternatives, doesn’t it?”
“You mean—”
“Well, the first alternative would be that Colonel Protheroe was dead already—but I don’t think that’s the most likely one. To begin with he’d only been there about five minutes and she or I would have heard the shot, and secondly, the same difficulty remains about his being at the writing-table. The second alternative is, of course, that he was sitting at the writing-table writing a note, but in that case it must have been a different note altogether. It can’t have been to say he couldn’t wait. And the third—”
“Yes?” I said.
“Well, the third is, of course, that Mrs. Protheroe was right, and that the room was actually empty.”
“You mean that, after he had been shown in, he went out again and came back later?”
“Yes.”
“But why should he have done that?”
Miss Marple spread out her hands in a little gesture of bewilderment.
“That would mean looking at the case from an entirely different angle,” I said.