“Come on!” he muttered, “something has happened here. Uncle is in New York, of course. He hasn’t had time to get back from delivering the mail we flew in. But where is the control room crew, and the hangar man, and Doc, and—Chick?”

Up the stairway, not replying, Garry followed him.

“Nobody in here!” Don turned a dismayed, and frightened, look on his chum, who responded with equal concern in his face.

“Something has happened,” whispered Garry.

At once he became practical.

“Don, we can’t stay here to find out what’s wrong. You want to capture the Demon. Run down and check your fuel, while I telephone the police station and report this—and ask for help on our ‘round-up.’”

Don raced back down the stairways.

Garry, rejoining him, a scant ten minutes later, was very sober.

“Chief wasn’t at the station,” he reported. “Man at desk seemed to be half asleep. Said the Chief had been called away on a special errand. Wouldn’t say how soon he could get help out here. There’s a mystery about all this, Don. What shall we do?”

“Run up and leave a note for Uncle,” Don counseled. “I’m filling the tank. If we can’t get help, we’ll handle this ourselves!”