“Then all we have to do is to find a man with an—” Al was not allowed to finish. Bob broke in, as older brothers like to do.
“Yes—get ‘the man in the gray suit!’ How many indelible pencils do you suppose there are in this country?”
“All right!” Al took the matter good-humoredly. “Anyhow, if a man wrote it and a man read it and threw it away—two hands have handled it.” He put it carefully in his pocket. “There may be fingerprints.”
“What good will they do?” asked Curt. “The mystery is all done with.”
“No it isn’t!” cried Bob, holding up his hand.
“Listen!”
From above came the drone of an airplane engine.
CHAPTER II
AT ROCKY LAKE
“I hear it!” exclaimed Al. He ran out onto the turf that had been used as a runway, probably, when the airplane took off.
“So do I,” agreed Curt, following him. “But I don’t locate it.”