“Friday night, of course, silly!”

But Garry grinned more widely. The others wondered, but waited.

“What has happened on four successive Friday nights, around Mystery Airport?” he demanded.

“The spook has appeared,” Chick volunteered.

Garry nodded.

“And what did I get to guard us against spooks?”

They remembered the small bag John’s Indian father had called a “charm” to clip ghost wings.

“What was I to do with it?” asked Garry, excitedly.

“You were to wear it all the time—let’s see—for seven days!”

As he spoke, Don caught his breath.