“We know for the purposes of our search. Obviously we can’t go tailing into Cayley’s bedroom and tapping his wardrobes; and obviously, therefore, if we are going to look for it at all, we must assume that it doesn’t begin there.”

“Oh, I see.” Bill chewed a piece of grass thoughtfully. “Anyhow, it wouldn’t begin on an upstairs floor, would it?”

“Probably not. Well, we’re getting on.”

“You can wash out the kitchen and all that part of the house,” said Bill, after more thought. “We can’t go there.”

“Right. And the cellars, if there are any.”

“Well, that doesn’t leave us much.”

“No. Of course it’s only a hundred-to-one chance that we find it, but what we want to consider is which is the most likely place of the few places in which we can look safely.”