ale of the
brothers.

"Oh! If I would only get strong enough go with you!" he exclaimed
regretfully.

"Don't worry, you will be strong soon," said Mrs. Racer kindly.

"It was rather mean of us to go away and leave you all alone, momsey,"
spoke Frank. "And Paul, too. But when Bob called us we just couldn't
resist."

"I'll forgive you," said the mother. "I won my golf match after all,
and perhaps if you had followed me over the links I might not have done
so."

"And I didn't mind being left alone," added Paul. "I'm so glad you got
the whale."

"And we may get your motor boat, and find out who that strange man is,"
said Frank.

"Now go slowly," advised Mr. Racer. "I don't want you boys getting
into trouble and danger. I think I had better attend to this matter
myself, only I can't very well stay away from the office to-morrow."

"Oh, we can do the work all right," declared Frank. "We'll go in our
sailboat, it won't take us long. Perhaps Paul will be strong enough to
come along."

"I wish I was," and the invalid shook his head. "But somehow I don't
feel so well to-night."

"Then we must have Dr. Martin look at you," decided Mr. Racer, and, in
spite of Paul's protests the physician was summoned by telephone.

"It is nothing," he said after examining Paul. "He exerted himself a
little too much to-day. He must be quiet for a couple of weeks yet and
he'll be all right."

"Then that means no trip for you to-morrow," said Mrs. Racer kindly.
"Never mind, I'll amuse you while the boys are away pretending they are
detectives," and she smiled at Paul.

It was about nine o'clock when Frank happened to remember that he had
left aboard their sloop _Gull_ a book of adventures in which he was
much interested.

"I'm going down and get it," he announced. "I won't be long."

"I'll go with you," offered Andy, and the two started off toward the
mooring place, which was near the big public pier. The boys kept a
light skiff tied to the float and in this way they used to row out to
the sailboat.

As they approached the pier they heard confused shouts and cries coming
from the direction of the bay.

"Something's going on!" cried Frank, breaking into a run.

"Yes. Sounds like someone in trouble," added Andy as he hollowed.

Once more came the cry, and this time the brothers could make it out:

"Fire! Fire! Fire!"

They turned a corner of the street that led straight out on the long
pier, and there caug