This key fitted as well as the other. A long coil of brown leather hose hung within, and in a corner lay a piece of chamois leather evidently used for polishing the brass fittings. This Hewitt pulled aside, and there beneath it lay another and cleaner piece of chamois leather, neatly folded and tied round with cord. Hewitt snatched it up. He unfastened the cord; he unrolled the leather, which was sewn into a sort of bag or satchel; and when at last he spread wide the mouth of this satchel, light seemed to spring from out of it, for there lay a glittering heap of brilliants! "What!" cried Plummer, who first got his speech. "Diamonds! Samuel's diamonds!" "Diamonds, at any rate," replied Hewitt, "whether Samuel's or somebody else's. But they can't have been there long. How often is this cupboard opened?" "Every Saturday reg'lar, sir," replied the housekeeper; "just to dust it out and see things is right." "Now, see here!" said Martin Hewitt, "I've had luck in my conjectures as yet, and I'll try again. Here is what I believe has happened. Every word that Samuel told me about the theft of those diamonds was true, except as to their ownership. Denson has planned all along to rob him of as big a collection of diamonds as he could prompt him to get together, and he has played up to this for months. His smaller dealings one way and another were ground-bait. Very artfully he let Samuel take the diamonds safely away once, in order that he should be less watchful and less suspicious the second time. This second time he does the trick exactly as we see. He hangs up the imaginary American's hat, he escapes by the fanlight, and he goes out by the back way to avoid the housekeeper's observation. He has arranged beforehand for this, too. He has seized an opportunity when the housekeeper has been out of his box to get wax impressions of these two keys, and he has made copies of them. And here we come on a curious thing. It is easy enough to understand why he should foresee and get himself a key for the back door, in order to make his escape. But why the key of the hose-cupboard? Why, indeed, should he leave the diamonds behind him at all? It is plain that he meant to come back for them--probably at night. He would have been wholly free from observation in that quiet courtyard, and he could let himself in, get the diamonds, and leave again without exciting the smallest alarm or suspicion. But why take all the trouble? Why not stick to the plunder from the beginning? The plain inference is that he feared somebody or something. He feared being stopped and searched, or he feared being waylaid _sometime during yesterday_. By whom? There's the puzzle, and I can't see the bottom of it, I confess. If I could, perhaps I might know something of last night's murder.