“Here we are at the top. Now for the test.”

The young inventor flashed on a powerful searchlight. “All I have to do is to connect this through a switch, aim my light at a window in our house, take up this microphone and say, ‘Hello father!’ He hears me and no one else in the world can. He—

“What!” he exclaimed in consternation. “The current is off. Someone cut the light cable!”

“More than that!” Johnny’s tone was sober. He was looking over the side of the balloon basket in which they rode. “The cable that holds us has been cut! We’re drifting!”

“You’re right!” Consternation sounded in the older boy’s voice. “We’re going out into the night, over black waters. And there is no ballast!”

“They got us, those two!” Johnny muttered.

“What two?” Felix demanded.

“I saw them on the grounds, a tall one and a short one—anyway I saw their shadows. Should have told you.”

“Oh!” Felix groaned. “Wonder what we’ve done to them. But they haven’t got us—not yet!” There was courage and high resolve in Felix Van Loon’s tone. “We’ll beat them yet. You’ll see!”

Would they? Johnny silently wondered.