unable to run down
the smuggling ships or the receiving parties ashore. Well, this plane
warns the ships away from the vicinity of the sub chasers, and also
directs the landing of the radio-controlled boats with their cargo at
lonely spots where there are no guards. Yes, sir, I believe that is
the way it has been worked."

He fell silent, and sat with brow wrinkled in concentrated thought.
The boys respected his silence, and also were busied with their own
thoughts.

"There is one thing that has got to be done," said Captain Folsom,
presently.

There was a gleam of determination in his eye.

"You mean the radio-controlled plane must be put out of commission?"
asked Frank quickly.

"You have read my thought," accused Captain Folsom. "Yes, that is just
what I was going to suggest. But how to do it, with no evidence
against Higginbotham or this mysterious individual living at the
Brownell house, is beyond me."

"Jack's a shark at the use of radio," declared Bob. "Perhaps he can
suggest some method."

All turned toward Jack.

"It wouldn't do, of course, to make a raid and capture the plane and
their radio plant?" Jack asked.

Captain Folsom shook his head.

"No," he said. "That wouldn't do, for a number of reasons. In the
first place, as I said, we have no evidence that would stand in court
that Higginbotham or anybody else connected with the matter is a
law-breaker. It may even be that whoever is behind the plot has
obtained a government license for the operation of the radio station.
The power of these bootleggers reaches far, and goes into high places.
Therefore, we cannot afford to make an open attack.

"But, in the second place," he added, leaning forward and uncrossing
his legs; "what good would that do? It would only warn the Man Higher
Up that we were on his track. We don't want him warned. We want to
close in on him. For I do believe you boys have given us a lead that
will enable us to do so. At the same time--we do want to put that
plane out of commission."

"Look here," said Jack, suddenly. "It's strange, if with our airplane
and our own radio plant, one of the most powerful private plants in
the world, certainly in America, it's strange, I say, if with this
equipment we are not enabled to work out some method for accomplishing
your ends.

"But, let's think it over. Let's sleep on it. I have the glimmerings
of an idea now. But I'm tired. It's been a hard day. Suppose we all
turn in and talk i