"The one of which we found the envelope?" Bart inquired.
"That's the one. Well, these men evidently are mixed up in the case. It seems to concern property. Maybe Frank has some property and will not give it up."
"If Frank has any property he has a right to it!" said Fenn with emphasis. "Frank's done nothing wrong, but he certainly is acting queer."
"Then I don't know what to make of that reference to a sanitarium. They shut the door at that point and I couldn't hear any more."
The three boys discussed the subject from all sides, but could come to no solution of the mystery. That the men had referred to Frank, Ned was sure, and his chums partly agreed with him.
"Of course there are a number of boys named Frank," said Bart. "But when they spoke of Frank's uncle, Mr. Dent, it must be they meant our Frank."
"There's another thing," spoke Ned. "They mentioned pulling the wool over Mr. Dent's eyes. I wonder if we had better warn him."
"What could we tell him?" asked Fenn.
"I could tell what I heard," replied Ned.
"Which wouldn't be enough to do any good, and it might cause a lot of trouble," said Bart. "I think we'd better let this thing alone. Frank may tell us something that will give us an opening to talk to him about this matter, and you can then tell him what you heard the men say."