"I'm not sure about that," answered his cousin. "When I looked at the grindstone next day there were spots of candle-grease on the wooden frame."
"What if there were?" interrupted Guy. "Henry may have taken a light in there late in the afternoon. Because there were a few spots of grease about, it doesn't prove that some one was working there in the middle of the night. Besides, supposing the knife was ground on our stone at that unearthly hour, it doesn't explain anything. It doesn't show what earthly object there could be in making the blade as thin as possible, and then throwing it into the pond."
"Oh, of course it doesn't," answered Brian; "but if you're ever going to get at the explanation of a thing like that, you must begin at the beginning, and ravel it out bit by bit. I believe it began that night when Elsie heard the stone turning, and I shall continue to think so until I have reason to believe otherwise."
"Oh, you're talking nonsense!" said Guy, who could think of no better reply to make. "Now, let's get on with our work."
It so happened that at the same time the children were talking over the strange loss and reappearance of the carving-knife, the subject was also being discussed in the dining-room.
"If I hadn't been quite sure that Guy was speaking the truth, I should have set it down as his doing," said Mrs. Ormond.
"It's neither of the boys' doing," answered her husband from behind his newspaper. "I saw that at once."
"How?"
"Why," replied Mr. Ormond, laying down his paper, and reaching for the knife, which lay on a side table, "it's a difficult matter to grind a blade as thin as that. No boy did it; at least that's my opinion. It was done by a man, and one who knew what he was about.
"I shall be at the police court on Monday," the speaker continued after a pause, "and I have a good mind to ask Evans, the sergeant, to step round and have a look at it. I'm inclined to think there's more in this matter than may appear on the surface."