that you can see into people's pockets and all that sort of thing as well."
Antony laughed and denied it cheerfully.
"Then how do you know?"
"You're the perfect Watson, Bill. You take to it quite naturally. Properly speaking, I oughtn't to explain till the last chapter, but I always think that that's so unfair. So here goes. Of course, I don't really know that he's got it, but I do know that he had it. I know that when I came on him this afternoon, he had just locked the door and put the key in his pocket."
"You mean you saw him at the time, but that you've only just remembered it—reconstructed it in the way you were explaining just now?"
"No. I didn't see him. But I did see something. I saw the key of the billiard-room."
"Where?
"Outside the billiard-room door."
"Outside? But it was inside when we looked just now."
"Exactly."
"Who put it there?"
"Obviously Cayley."
"But—"
"Let's go back to this afternoon. I don't remember noticing the billiard-room key at the time; I must have done so without knowing. Probably when I saw Cayley banging at the door I may have wondered subconsciously whether the key of the room
