, the bullet would be slowed by the water.

He heard the sound of a motor and recognized it as the runabout. The
sound faded again. Scotty was going through some kind of maneuvers.
Then, in a short time, another motor made itself felt, more than heard.
The slower beat identified it as Orvil Harris's crab boat. He was
nearing the cove!

Like all divers, Rick's ears were sensitive to pressure changes. Sensing
when the depth lessened, he knew he had reached the cove itself. Now to
find the payload--if it was a payload. His groping hands began the
search.

The first foreign object he touched was a cord. It was the wrong
thickness for his own line, and he felt along it until he came to a
soft, round mass, and knew he was touching one of Orvil's crab baits. He
grinned in spite of the mouthpiece. Wouldn't Orvil be surprised if a
diver came up hanging to his bait!

He let the crab line drop and continued his search. Once, Orvil passed
within a few feet of him, and Rick wondered if the crabber had noticed
the air bubbles from his regulator.

Rising ground told Rick he had reached the end of the cove. He turned
left and held his course for about twenty feet, then turned left again,
heading back toward the cove entrance. His hands never stopped moving,
probing the mud for a trace of fish line. He crossed another of Orvil's
crab lines, and kept going until pressure change told him he was back in
the deeper water at the creek entrance. He turned right again. A check
of his compass told him he was on course.

His groping hands trailed over a thin line. He grabbed it, and stopped
his flutter kick. Then, moving with care, he turned and followed the
line. His pulse was faster now, and he rigidly controlled his breathing.
Fast breathing wouldn't do, and he would have to be careful not to let
out a sigh that would cause bubbles to gush upward in one big rush.

A hand found the end of the line and the smooth cylinder to which it was
attached. Orvil passed very close, and Rick looked upward. He could see
the white circle of water around the single propeller.

Now to find out what he had. His hands stroked it from one end to the
other. One end was rounded. The other was a circle with an odd-shaped
hole running into it. Rick poked his finger in, but couldn't feel the
end of the depression. The only protuberance on the thing was a band
near the rounded end. The band felt like metal, and had two rings
projecting from it. The rest of th