"Mebbe you're right," he said doubtfully. "I don't know 'bout such things. But who'da thought that cave would be discovered. Why, I just come on it accidental like onct when I was wanderin' through these hills."
"Boys, there's only one thing to do," said Jack in a determined voice, "and that's to investigate."
"Righto, Jack," said Frank eagerly. "Here's our chance to get back our airplane."
"You said it," declared Bob. "Let's go."
"Not so fast," said Jack. "First we must have a plan of campaign. Tom, what's the lay of the land? How far away is the cave? Would it be better to leave our horses here and approach on foot?"
"Cave's not more'n half a mile from here," answered Tom. "It's just around the shoulder o' this hill we're on right now and near the top. I tole you 'bout that big rock in front o' the entrance an' them three lonesome trees at the foot that give you a bee-line to the rock. Well, we can git to them trees without bein' noticed an' tie our horses there an' then sneak up afoot."
"Is there only the one entrance to the cave?"
"Only one," answered Tom. "There's a kind o' chimney up through the rock to the top o' the hill. But nobody couldn't git out there in much of a hurry. We won't have to worry 'bout that."
Frank had an idea.
"How far would those fellows in the airplane have to go to reach the cave after landing?"