"He overheard part of our conversation on the ferry-boat the other night," went on the book-keeper, hastily, "and from that he judged we must be plotting to rob Mr. Sumner."
"Well, that's rich!" Mr. Allen broke into a laugh. "Excuse me, Sumner, but I can't help it. Of course, you don't think any such thing."
"No, I can't say that I do," replied the elderly broker, slowly. "But"—he turned to the safe—"the tin box is gone and I would like to know what has become of it."
"Better call in the police," suggested Hardwick. "And in the meantime keep an eye on this boy."
"And also on that man," added Hal, pointing to the book-keeper.
Mr. Sumner was in deep perplexity. He ran his hand through his hair.
"Let us talk this matter over first," he said. "You say, Hardwick, you left Carson alone in the office yesterday afternoon?"
"Yes, sir."
"How long?"
"Not more than ten minutes."