out who you are, what you have to do with a boy named
Paul, why you have his motor boat in tow, and why you entered our house
like a thief in the night."

"Hu! That's a lot of questions. And I suppose you think they'll be
answered," commented the man, in sneering tones.

"I do," said Frank calmly. "Where are you going with that boat?"

"None of your business!" snapped the man. "And I want to tell you one
thing more. You've got to quit trailing after us, too!"

"Suppose we refuse?" asked Andy.

"Then it will be the worse for you. Meldrick, just run that brass
cannon over on this side."

A moment later the muzzle of a small brass gun was pointed menacingly
at our heroes.

"There's my answer," went on the mysterious man. "If you persist in
following us you'll be plugged below the water line. Now you go back
where you came from, and keep away. Don't try to meddle with what
doesn't concern you."

"This does concern us--or, rather a friend of ours," said Frank
determinedly. "And what's more, we're going to swear out a warrant for
your arrest for setting fire to our boat with a bale of hay."

The man on the rail started.

"Are you going to turn back?" he shouted.

"No!" declared Frank.

"Get ready to fire," said the scoundrel calmly.

"I guess they've got us," spoke Andy, in a low voice to his brother.
"We can't risk being fired at."

"No, I suppose not," answered Frank bitterly. "We'll have to run back."

He let the head of his craft fall off in the wind.

"That's more sensible," commented the man on the rail. "Good-bye!" he
called sarcastically as the vessels separated, the one towing the
damaged motor craft forging ahead, while the _Gull_ sailed off on the
backward tack.

There were bitter feelings in the hearts of Frank and Andy Racer. They
had almost solved the mystery, only to lose at the last moment. But
they resolved not to give up.

CHAPTER XVI

ON THE SEARCH

For some time after they had been ordered back from their pursuit of
the strange vessel neither Frank nor Andy said anything. They were
thinking too hard for mere words. Finally the younger lad expressed
himself.

"Well, wouldn't that spoil your clam chowder?"

"It sure would," agreed Frank, who was used to queer remarks from his
brother.

"He must be up to something crooked or he wouldn't be so anxious to
have us stop following him," went on the younger Racer lad.

"That's right. And I was so sure I'd find