Part 10 (2/2)

Bill had dropped down on the gra.s.s, and Cayley took his place on the seat, and sat there heavily, his elbows on his knees, his chin on his hands, gazing at the ground.

”I want you to be quite frank,” he said at last. ”Naturally I am prejudiced where Mark is concerned. So I want to know how my suggestion strikes you who have no prejudices either way.”

”Your suggestion?”

”My theory that, if Mark killed his brother, it was purely accidental as I told the Inspector.”

Bill looked up with interest.

”You mean that Robert did the hold-up business,” he said, ”and there was a bit of a struggle, and the revolver went off, and then Mark lost his head and bolted? That sort of idea?”

”Exactly.”

”Well, that seems all right.” He turned to Antony. ”There's nothing wrong with that, is there? It's the most natural explanation to anyone who knows Mark.”

Antony pulled at his pipe.

”I suppose it is,” he said slowly. ”But there's one thing that worries me rather.”

”What's that?” Bill and Cayley asked the question simultaneously.

”The key.”

”The key?” said Bill.

Cayley lifted his head and looked at Antony. ”What about the key?” he asked.

”Well, there may be nothing in it; I just wondered. Suppose Robert was killed as you say, and suppose Mark lost his head and thought of nothing but getting away before anyone could see him. Well, very likely he'd lock the door and put the key in his pocket. He'd do it without thinking, just to gain a moment's time.”

”Yes, that's what I suggest.”

”It seems sound enough,” said Bill. ”Sort of thing you'd do without thinking. Besides, if you are going to run away, it gives you more of a chance.”

”Yes, that's all right if the key is there. But suppose it isn't there?”

The suggestion, made as if it were already an established fact, startled them both. They looked at him wonderingly.

”What do you mean?” said Cayley.

”Well, it's just a question of where people happen to keep their keys. You go up to your bedroom, and perhaps you like to lock your door in case anybody comes wandering in when you've only got one sock and a pair of braces on. Well, that's natural enough. And if you look round the bedrooms of almost any house, you'll find the keys all ready, so that you can lock yourself in at a moment's notice. But downstairs people don't lock themselves in. It's really never done at all. Bill, for instance, has never locked himself into the dining-room in order to be alone with the sherry. On the other hand, all women, and particularly servants, have a horror of burglars. And if a burglar gets in by the window, they like to limit his activities to that particular room. So they keep the, keys on the outside of the doors, and lock the doors when they go to bed.” He knocked the ashes out of his pipe, and added, ”At least, my mother always used to.”

”You mean,” said Bill excitedly, ”that the key was on the outside of the door when Mark went into the room?”

”Well, I was just wondering.”

”Have you noticed the other rooms--the billiard-room, and library, and so on?” said Cayley.

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