“And who may your father be?” inquired Mr. Perry with provoking calmness.

“You’ll find out who my father is, just you wait.  You haven’t any right here.  These islands belong to my father and—­”

“Oh—­ho!” interrupted Mr. Perry in tone of sudden discovery.  “So that’s the way the wind blows, is it?  I get you now.  You’re the son of one of those kidnappers.”

The boy’s face twitched, possibly with pain, more likely with alarm at his having betrayed his identity so foolishly.

“We’ll get down to the bottom of this mystery yet,” Cub declared confidently.

“Yes, all we need is a little mathematics, Mr. Perry, and we’ll soon solve the problem.”

“We’ve had some mathematics already,” Mr. Perry smiled.

“I didn’t see it,” returned Cub.  “Maybe I’m slow.”

“No, you haven’t got farther than your One’s in the addition table.  You can add 1 to any other number, but you can’t tell how much 2 plus 2 are.”

“All right, I’m foolish,” admitted Cub.  “Spring your joke.”

“This is a rather serious situation in which to spring a joke,” reminded the “foolish boy’s” father.  “But didn’t you hear me put two and two together when this fellow declared that this island belonged to his father?”

Laughter greeted this sally, in spite of the seriousness of the situation.

“By the way, I wonder if we haven’t got this youngster’s father a prisoner on the Catwhisker,” Mr. Perry continued.  Then he turned toward the youth on the cot and inquired: 

“Is your father a tall, angular fellow with a smart, flip way of talking, and do his friends call him captain?”

The catapult victim did not answer, but the expression on his face was all the evidence that was needed to indicate what an honest reply would have been.

“I thought so,” said Mr. Perry.  “Now, would you like to make a trip down to the landing and occupy a stateroom in the Catwhisker with your father?  The Catwhisker, by the way, is a yacht in which we made a trip from Oswego, New York, to rescue a boy marooned by some young scamps on this island.  After he was marooned, your father and his friends kidnapped him and took him away.  Now, what we want to know is, where is he?”

Still the wounded prisoner made no reply.

“There’s going to be some awful serious trouble for your outfit if that boy isn’t returned,” Mr. Perry went on, waxing fiercer and more fierce in his manner as he purposely worked up a towering rage for the sake of its effect on the boy on the cot.  “Would you like me to turn you over to the father of the boy whom your scoundrel gang kidnapped?  What do you think would happen to you if he got hold of you?  Well, he’s on the boat down at the landing, and your father is there too, under lock and key.  And before long we’re going to have the whole gang of you under lock and key.  Now, don’t you think it is best for you to give up your secret and tell where that boy is?”