t for the attempt to destroy the
airplane. Plain, too, was the fact that Higginbotham was engaged in
some nefarious enterprise.

For several seconds longer, after Higginbotham and his companion had
gotten beyond earshot and were lost to view among the trees, Jack
remained quiet but inwardly a-boil. Then he turned to Captain Folsom
and Tom Barnum, crouching beside him.

"What an outrage," he whispered, indignantly. "Poor Bob and Frank. To
have their airplane damaged just because that scoundrel thought we
were prying into his dirty secrets. I wish I had my hands on him."

Suddenly his tone took on a note of alarm.

"Why, where are Bob and Frank?" he demanded. "They were here a moment
ago."

He stared about him in bewilderment. The others did likewise. But the
two mentioned could not be seen. With an exclamation, Jack rose to his
feet.

"Come on," he urged. "I'll bet Bob decided to go for the fellow who
burned his plane and take it out of his hide. When that boy gets
angry, he wants action."

He started striding hastily down toward the beach, alongside the wire
fencing. The others pressed at his heels. Presently, they caught the
glint of water through the trees, and then, some distance ahead,
caught sight of two figures moving out from the grove onto the sands
on the opposite side of the fence. Jack increased his pace, but even
as he did so two other figures stole from the woods on the heels of
the first pair.

Involuntarily, Jack cried out. The second pair leaped upon the backs
of the first and bore them to the ground. The next moment, the air was
filled with curses, and the four figures rolled on the sands.

"Come on, fellows," cried Jack, breaking into a run, and dashed
ahead.

He broke from the trees and discovered the boundary fence came to an
abrupt end at the edge of the grove. It was here Bob and Frank, he
felt sure, had made their way and leaped on Higginbotham and the thug.
For so he interpreted what he had seen.

As he came up the fight ended. It had been bitter but short. Frank was
astride Higginbotham and pressing his opponent's face into the sand to
smother his outcries. Bob had wrapped his arms and legs about the city
ruffian and the latter, whose curses had split the air, lay face
uppermost, his features showing contorted in the moonlight. Bob knelt
upon him. As Jack ran up, he was saying:

"You want to be careful whose airplane you burn."

An exclamation from Captain Folsom drew Jack's at