“That’s better, Bill. Don’t be afraid of getting away from the accident idea. Well then, your new theory is this. Mark confesses to Cayley that he shot Robert on purpose, and Cayley decides, even at the risk of committing perjury, and getting into trouble himself, to help Mark to escape. Is that right?”

Bill nodded.

“Well then, I want to ask you two questions. First, is it possible, as I said before dinner, that any man would commit such an idiotic murder⁠—a murder that puts the rope so very tightly round his neck? Secondly, if Cayley is prepared to perjure himself for Mark (as he has to, anyway, now), wouldn’t it be simpler for him to say that he was in the office all the time, and that Robert’s death was accidental?”

Bill considered this carefully, and then nodded slowly again.

“Yes, my simple explanation is a washout,” he said. “Now let’s have yours.”