"Wait, wait," called Bob, in a tense voice that reached the ears of all, and caused them to halt. "Keep your horses quiet and listen. There. I was right."
All sat silent, and distinctly there came to their ears the hum of an approaching airplane.
CHAPTER XVII
INSIDE THE CAVE
"What is it?" whispered Tom Bodine, to whom the sound was unfamiliar. "Sounds like machinery of some kind."
"It's an airplane," Jack answered.
"Airplane? An airplane?" said Bob, low voiced. "It's better than that. It's our airplane, if I know anything."
"Righto, Bob," agreed Frank. "I'd know the old baby's voice a mile off."
"They've shut off the motor," said Jack. "They must be going to land. But where in the world could they land in these hills and in this darkness, too?"
Tom Bodine slapped his knee.