pulled twice on the rope
in a signal to surface. Scotty motioned to him to lead the way.

As Rick started up, four metallic clangs, irregularly spaced, rang
faintly in his ears.

Tony, banging his tank in the signal for trouble! Rick instantly changed
course and followed the bottom, watching the water overhead for any sign
of the frogmen. When he had reached a spot below the point on the reef
where Tony should be waiting, he turned toward the surface, moving
slowly, searching for any sign of activity. There was no sign of
whatever had alarmed Tony.

He paused a few inches under the surface, then carefully put his face
into the air. Scotty surfaced beside him.

There was no sign of Tony. Rick peered through his mask and saw that the
boat was still anchored in the same place. There were figures on its
deck. Four of them--Four! He ripped his mask off for a clearer look, and
his heart skipped a beat. The frogmen had Tony!

CHAPTER XV

How Sings the Gay Sardine?

Rick and Scotty held a hurried consultation, mouth to ear.

"We'll have to get him," Scotty whispered urgently. He held up his spear
gun. "I've only got one shot in this."

Rick's instinctive reaction was the same. They had to rescue Tony! But
they also had a job to do.

"Wait," he cautioned. "They probably don't know we're here. Tony
wouldn't give us away. If they find out, we'll lose the pictures, and we
may make it worse for Tony. Let's stay right here and watch."

Scotty subsided. They floated motionless, eyes on the boat, peering to
penetrate the mist. The rain had let up somewhat, but the air was far
from clear.

Rick would have given the treasure they sought to be able to hear what
was being said on the boat. The three frogmen were all facing Tony, and
the conversation seemed to be pretty animated. Then, as he watched, the
boat pulled up anchor. It moved north.

"They're taking him to their house," Scotty gasped.

The boys swam frantically for shore, recklessly crossing the reef
without regard to the danger of cutting themselves on the sharp coral.
They reached the beach and shed tanks and equipment under the palms,
then raced for the frogmen's house.

They could see the lights of the boat as it rounded the northern tip of
the island, and, lying among the palms, they watched it tie up at the
pier. Tony and the three frogmen got off and walked down the pier. Rick
strained to see, and could not find any sign that Tony was covered by a