“I know now where that strange interference in our radio receivers comes from.”

“Is that so?” demanded Jack, excitedly. “It was cutting up didoes just a few minutes ago, just before you arrived. Had been for some time, too.”

“Well,” said Bob, “that’s not to be wondered at. For when I followed Peg Leg’s tracks through the trees I discovered a radio station tucked away in a hollow behind the timber, with sandhills hiding it on the landward side. I watched for a while from behind a tree, but couldn’t see anybody. Then I hustled here to tell you fellows about it.”

Puzzled, the trio regarded each other in silence. Presently Jack spoke.

“Look here, fellows. There’s something queer about this. A mysterious radio station, hidden away, that sends a continuous wave on a hitherto unused wave length. This has been going on for a week. What does it mean? Then there is this man, this Peg Leg, whom Bob discovers arriving from the sea.”

“Let’s go together and investigate,” cried Frank, jumping to his feet. 10

“I’m with you,” declared Bob, also arising. “I would have gone up to the station and done that very thing, by myself, but—I don’t know—there was something about it all—something sinister.”

“Wait a minute, you fellows,” said Jack, also springing upright. “We can’t go putting our heads into trouble recklessly. Bob’s good sense prompted him when he refrained from pushing up to that radio station by himself. There is something sinister about this. That place is isolated, there are no roads near it, nobody ever hikes along that beach except us. How did the station ever come to be built? Why, the material and supplies must have been brought by boat. They couldn’t have been transported overland very well.”

“What shall we do, though, Jack?” asked Frank, impatiently. “You can’t reasonably expect to have a thing like this rubbed under our noses without our going ahead and investigating.”

There was so much plaintiveness in his voice, as of a child from whom a toy was being withheld, that Bob and Jack both burst into laughter. Then Jack sobered.