of Steve's
former tail on this island. Hasn't it occurred to you that those fancy
frogmen, as you call them, would have made some overt move by now if
they were really interested in us?"

"Dropping the chicken was an overt move," Rick pointed out.

"Yes and no. I'd prefer to call it a not-too-subtle warning. Yet they
haven't tried to interfere with your diving around the wreck."

"I've wondered about that," Scotty offered, "and it seems to me they've
satisfied themselves that our interest is just in the wreck, and not in
whatever they have hidden underwater. If they have anything hidden, I
mean. As long as we stick with the wreck, they have no reason for
causing trouble."

Tony agreed. "That makes sense to me. Perhaps you can answer this: Why
do they wear cold-water suits? It's appreciably cooler at twenty
fathoms, but it's certainly not cold enough for a suit."

"We only stay down fifteen minutes," Scotty said. "If we stayed down
longer we might get chilled. The water isn't warm by any means down by
the wreck."

Rick had a thought. "We're used to cold water, remember? Diving off
Spindrift would chill a polar bear, even in summer. Suppose these people
had done all their diving in tropic waters? This water would seem cold
to them, particularly down deep."

It was nearly dark now, only a glimmer of light in the west. The four
sat on the front porch of the cottage.

Zircon asked, "Did you monitor the radio tonight, Rick?"

"Yes, but there was no word from Steve."

"Don't you think he might like to know about the presence of his shadow
on Clipper Cay?" Tony inquired.

Rick pointed to the Sky Wagon resting on the beach. "Trouble is, that's
our only communication. I could contact the St. Thomas airport and
request that they pass a message, but that would be like broadcasting it
to the world. Steve might not like it."

Zircon's deep voice cut into his comment. "Look! Our friends are
apparently going to do some night work."

There were lights on the frogmen's boat, and it was putting out. As the
Spindrifters watched, it slowly approached the reef, then stopped.
Scotty got the glasses and examined the scene. "Something's up!" he
exclaimed. "I saw a diver go over the side!"

Hobart Zircon coughed self-consciously. "Do you know, I have taken a
certain amount of pride in the fact that I am by nature a conservative
individual with a highly developed capacity for minding my own
business."

Rick wondered what on ea