Henry Robinson, the caretaker of the Tower Mansion, was the father of one of their closest chums. Perry Robinson, nicknamed “Slim,” was to have accompanied them on their jaunt to the woods that day but had failed to appear. The reason was now evident.

But that Henry Robinson should be accused of the robbery seemed absurd. The boys had met Slim’s father and he had appeared to them as a good-natured, easygoing man, the soul of truth and honesty.

“I don’t believe it,” whispered Frank.

“Neither do I,” returned his brother.

“What makes you suspect Robinson?” asked Mr. Hardy of Hurd Applegate.

“He’s the only person besides my sister and me who ever saw that safe opened and closed. He could have learned the combination if he kept his eyes and ears open. I believe he did.”