to throw Tom off balance, but the cadet was not to be denied. He
swung the heavy pipe again and again, landing hard, telling blows on the
arms and shoulders of the burly truck driver. Finally a solid blow
caught Cag on the side of the head and he slumped over unconscious. Tom
leaned over him, grabbed the wheel, and maneuvered the big truck back
onto a straightaway course. A minute later he brought the truck to a
stop.

Tom jumped out and pulled Cag after him, taking a bottle of water from
the small compartment behind the driver's seat. He splashed some on the
man's face, and while Cag moaned and came to, Tom drank his fill. He
hadn't realized that he was so thirsty.

"Cag," said Tom coldly, when he knew the man could understand him,
"I'll beat your ears off if you don't tell me who put you up to this!"

Cag was silent. Tom stepped in and slapped the man across the face.

"Come on! Talk!" he snarled.

Dirty, his clothes ripped, his hands bloody, Cadet Tom Corbett did not
look like the carefree young cadet that Cag had met a few hours ago. He
was frightened and began to whine.

"Talk or I'll slap you silly!" Tom growled.

Cag saw the wild rage in Tom's eyes and began to stutter.

"The trucking outfit! Just find out who owns this trucking outfit and
who would gain if the projectiles failed."

Tom was back in the cab in a flash. He started the mighty jets and began
to engage the clutch.

Cag leaped up. "You can't leave me here in the desert! I'll die."

Tom looked at the man, threw out the rest of the food and water from the
compartment, and gunned the huge truck down the highway.

Eight hours later Tom rolled into Marsport, stopping the big truck at
the first Solar Guard substation he could find.

He raced inside without cutting the jets of the truck and reported to a
sergeant seated behind the desk, reading.

"I'm Cadet Tom Corbett!" he shouted. "I've got to get in touch with
Commander Walters at the Academy right away."

"Stand where you are, Corbett!" said the sergeant, jumping up and
leveling a paralo-ray gun at him. "You're under arrest!"

Tom stared, and then, spinning on his heels, dashed out of the station,
the guard's ray blasts spitting at his heels. Jumping into the truck, he
gunned the jets and roared off into the dark Martian night.

[Illustration]

CHAPTER 12

"Aw, shut your big Venusian mouth!"

As Roger's voice roared over the intercom loud-speaker of the speedy
rocket scout