there."

Dawson did just that, and a couple of minutes later he set the Vultee
down light as a feather and taxied it over toward the Administration
Building. He braked to a stop eventually, unsnapped his safety and
parachute harness, and climbed stiff-legged down onto the ground. Freddy
Farmer joined him, and they were just starting to get some of the flight
stiffness out of their legs when a major came out of the Administration
Building and walked over to them.

"Captains Dawson and Farmer?" he asked with a smile.

"Yes, sir." Dave replied with a salute. "I'm Dawson. And you are Major
Parker, Yank commandant here, sir?"

"That's right," the senior officer replied. "Welcome to Trinidad. Word
came through that you were making a survey flight along our South
American bases. I think you'll find we're not doing so badly here at San
Fernando. Here, this came through about half an hour ago. It's addressed
to you both. Needless to say, we didn't try to decode it. I don't
believe we have that code in the base book, anyway."

The major held out a small yellow envelope. Dawson took it, ripped it
open, and withdrew a single sheet of paper. His heart did a loop in his
chest when he saw that the coded message was signed, "Tiger." That was
the signature Colonel Welsh used whenever he contacted the boys in
secret. The major had been quite correct, too. The code used by Colonel
Welsh was not to be found in the regular base code book, because it was
a special one that the colonel had made up himself. This code was not
known by more than half a dozen men, two of them being Dawson and
Farmer. The value of such a code was that it was so made up that a
decoding book, or decoding wheel, was not needed. Once you knew the
code, you could read messages from the memory of what the various
letters and numbers and symbols meant.

Dave Dawson and Freddy Farmer looked at it together, while Major Parker
politely stared off across the base field. The true meaning of the
message became instantly apparent to them. Translated in their minds, it
read:

"Halt flight San Fernando. Arriving by air midnight. Serious
emergency developed. Maintain constant alert. Destroy evidence if
necessary. Important!

WELSH"

Dawson read the coded message three times, absently pulled off his
helmet and goggles, ran his fingers through his hair, and glanced
sidewise at Freddy Farmer.

"And that is strictly that," he said. "But I wonder what?