nothing. He was just as
puzzled over Connel's motive as ever. Obviously, the answer was not
here--or, if it was, they couldn't see it.

"Okay," he said. "Move out."

Scotty led the way back to the jeep. Rick got into the driver's seat and
started the motor. He backed and turned in the narrow space Connel's
jeep had created, and finally got his wheels straight for the run back.

From somewhere behind them a voice called, "_Parada!_"

"Who's that yelling at us to stop?" Rick asked.

"I can't see anyone," Scotty replied. His eyes were scanning the jungle.
"But I don't know anyone around here we want to talk to. I've got a
hunch we should get going."

Rick felt the same. He released the clutch and the jeep moved ahead.

"_Parada!_" the voice yelled again, and on the echo came the clear crash
of a rifleshot. A jagged star suddenly appeared on the windshield
between them!

Rick reacted instinctively. He shoved the gas pedal to the floor and
bent low, the skin of his back crawling with the expectation of a rifle
bullet hitting it. The jeep leaped ahead and he steered as best he
could. He shifted into second and the vehicle picked up speed. The rifle
snapped again and he heard the sound of the slug hitting metal in the
rear of the jeep. Then the trail turned and there was heavy jungle
growth between them and the unseen sniper.

Not until they reached the second station, a mile away, did Rick slow
down. He looked at Scotty, his face grim. "The place was guarded. What
else can you make out of it?"

"Just that," Scotty agreed. "The guard must have been making a tour
around the shot station. He got back just as we were taking off."

"Funny he didn't hear the jeep when we came," Rick said.

"Not very. Sound gets lost pretty fast in this heavy growth. You
couldn't hear us a hundred yards away. Probably there's just the one
guard, and he goes around the station in a big circle."

"I'll buy it," Rick agreed. "But why? Why guard a chunk of jungle with
nothing in it but some torn up yellow ground?"

"When I find out," Scotty replied, "I'll let you know first thing."

CHAPTER X

The Volcanic Pipe

Hartson Brant and Julius Weiss were still at work in the conference room
when Rick and Scotty returned. David Riddle had gone, and the others had
evidently not finished placing the tiltometers.

The two listened to Rick's story in silence, then Hartson Brant sighed.
"I don't know how you do it, Rick. But if there's