Toward the end of the afternoon they were in sight of Rock Harbor, a small port, where they spied a schooner at anchor in the distance. Rock Harbor was not a shipping point of great importance, but there were always a number of miscellaneous craft in evidence.
To enter the harbor they were obliged to pass within a short distance of the schooner, swinging about beneath the bows of the vessel. As the Sleuth plunged through the water, in the very shadow of the ship, Joe suddenly gave an exclamation of surprise.
"Frank! Look up on deck—quick!"
Frank glanced hurriedly upward. He was just in time to see the figure of a boy moving away from the rail, but there was something familiar about the young fellow that made him look incredulously at his brother.
"Chet!"
"I'm sure it's him," returned Joe hurriedly. "I didn't get a very good look at his face, because he only looked over the rail and then he drew back—but I'm almost positive it was Chet!"
"But what on earth can he be doing on that schooner?"
"Probably he's a prisoner. Let's give him a hail."
They shouted the name of their chum half a dozen times, but their only response was from a villainous looking sailor who glared over the side at them and bade them get away from the ship.
"No use causing trouble," said Frank, in a low voice. "We'll go now, but we'll come back later."