"Do you know that you were followed?"
"By Rasmer?"
"No, by Gus Plum."
"Plum!" gasped Shadow Hamilton, and his face turned pale. "Are—are you certain of this?"
"That is what Ike Rasmer told me," and then Dave related all that the old boatman had said.
"That makes the mystery deeper," muttered Shadow. "It puts me in mind of a story I once—but I can't tell stories now!" He gave a sigh. "Oh, Dave, I am so wretched over this! I don't know what to do."
"I know what I'd do."
"What?"
"Go and tell Doctor Clay everything."
"I—I can't do it. He thought so much of that stamp collection—he'll surely send me home—and make my father pay for the collection, too."