“We’ll begin at the moment when Mark shoots Robert. Call it an accident; probably it was. Mark would say it was, anyhow. He is in a panic, naturally. But he doesn’t lock the door and run away. For one thing, the key is on the outside of the door; for another, he is not quite such a fool as that. But he is in a horrible position. He is known to be on bad terms with his brother; he has just uttered some foolish threat to him, which may possibly have been overheard. What is he to do? He does the natural thing, the thing which Mark would always do in such circumstances. He consults Cayley, the invaluable, inevitable Cayley.

“Cayley is just outside, Cayley must have heard the shot, Cayley will tell him what to do. He opens the door just as Cayley is coming to see what is the matter. He explains rapidly. ‘What’s to be done, Cay? What’s to be done? It was an accident. I swear it was an accident. He threatened me. He would have shot me if I hadn’t. Think of something, quick!’