give up the search if you don't get any more messages
from him," declared the boy's father.

"That's so," Cub admitted. "And if those men captured him and took him
away in their boat, this affair will have to remain a mystery in our
lives forever afterward."

"You'd better go back to the cabin and see if Bud and Hal got any more
messages from him," suggested Mr. Perry.

"That's the only hope left," said Cub as he turned to go.

But this "last hope" proved to be vain. Bud and Hal were both still
listening-in, but with little suggestion of expectancy on their
countenances.

"Anything more?" inquired the tall youth, unwilling to put his question
in negative form, in spite of the fact that his better judgment would
have dictated it thus.

Both listeners shook their heads.

"Then that's the end of our search," Cub declared with a crestfallen and
disgusted look.

"Why?" asked Bud.

"Answer the question yourself; it's easy,"

"I don't see why we should give up just because we've run up against an
obstacle a little worse than any we've met before," said Hal.

"All right," Cub challenged. "Let's see what you propose to do."

"Well," Hal responded slowly; "we could go on till we found--"

He stopped and looked foolish.

"Found what?" asked Cub. "The island? How would you do that without
something to guide your radio compass?"

"That's so"; Hal admitted, with another foolish look.

"It's too bad," Bud broke in, with tone well suited to his words.

"I suppose the next thing for us to do is to look for a tie-up for the
night." said Hal indicating his sense of defeat by his change of subject.

"I think father is doing that now," replied Cub. "Guess I'll go and see
what his idea is on that subject."

By this time the Catwhisker was several miles beyond Grindstone Island
and was winding its way through a labyrinthine group to the north of
Grandview. The scenery here was so enchanting that Cub and his father
speedily agreed that the first convenient, unclaimed natural harbor that
they discovered ought to be adopted as theirs for the night.

The season was well opened, and there were many boats on the river, so
many, indeed, that it seemed strange that any live, intelligent person
could be marooned on one of those islands, however vast their number,
without being able to call attention to his distress. However, there were
main highways in this, as in any other, semi-wilderness, and doubtless
some of the by-ways w