"I don't know who it can be. Did he go up into my room?"
"Yes, he did. He said he knew the way."
"I can't think who it was."
Gilbert went up stairs, and, to increase the mystery, there was his opera-glass on the bureau, where he usually kept it. It was directly in sight, so that the visitor must have seen it.
"I can't understand it," he said, perplexed. "Mordaunt, do you know of any friend of mine who has a black mustache?"
"Frank Oswald."
"He is considerably larger than I am. The servant said it was some one of my size."
"I can't think of anybody else."
"I don't see why he didn't take the opera-glass, if he wanted it, though it would have been rather bold, as I didn't authorize anybody to take it."
As there seemed no clew to the mystery, and as, moreover, Gilbert had no suspicion that the visitor was on an unlawful errand, he dismissed it from his mind.