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.

"I've only just thought about it while I've been sitting out here. You
live here haven't you ever noticed them?"

Cayley sat considering, with his head on one side.

"It seems rather absurd, you know, but I can't say that I have." He
turned to Bill. "Have you?"

"Good Lord, no. I should never worry about a thing like that."

"I'm sure you wouldn't," laughed Antony. "Well, we can have a look when
we go in. If the other keys are outside, then this one was probably
outside too, and in that case well, it makes it more interesting."

Cayley said nothing. Bill chewed a piece of grass, and then said, "Does
it make much difference?"

"It makes it more hard to understand what happened in there. Take your
accidental theory and see where you get to. No instinctive turning of
the key now, is there? He's got to open the door to get it, and opening
the door means showing his head to anybody in the hall--his cousin, for
instance, whom he left there two minutes ago. Is a man in Mark's state
of mind, frightened to death lest he