He was standing there quietly, gazing at them without a shadow of expression on his sinister face, as motionless as a statue.
When he saw that he was observed he called out:
"Leave this place!"
Tony throttled down the engine. The three boys stared at the man in the black hat as though he were an apparition.
"Leave this place!" he repeated, in a curiously metallic voice.
"We aren't doing any harm," replied Frank.
"Not now," said the stranger. "But don't land here."
"Why?"
"You don't have to ask why. This is private property. You can't land here. You'd better leave at once."
The boys hesitated. As though to emphasize his commands, the man in the black hat reached suddenly into his pocket and whipped out a wicked-looking revolver. Then he folded his arms, tapping the barrel of the revolver against one shoulder very deliberately.
"Turn that boat around and get out of here!" he snapped. "Don't come back. Don't ever come back. Don't ever try to land here. This is private property. If you ever do land here you'll be shot."
The boys were unarmed. They realized that
