rrender message, and if not obeyed,
you will open fire!"

Behind him, the three cadets of the _Polaris_ unit listened to the
decisive words of their commander and then let out an earsplitting yell.

"No time for celebrating," barked Strong. "We haven't caught him yet.
He's the slickest thing to hit this system since the reptiles climbed
out of the Venusian mud! It's going to be a case of our getting him
before he can disappear into the asteroid belt, so let's hit the high,
wide, and deep!"

Five minutes later, Strong and the boys were aboard their ship.

"Ready to blast off, sir," reported Tom. The curly-haired cadet's face
was still pale and drawn, showing the effects of his ordeal in space.

"Get me direct teleceiver contact with Captain Randolph on the rocket
cruiser _Sirius_," ordered Strong.

"Yes, sir," replied Tom. He turned to flip on the teleceiver, and a
moment later the captain's face appeared on the screen.

"Randolph here. What's up, Steve?"

"I've got Squadron Nineteen of the Martian reserve fleet heading for the
last reported position of the _Avenger_ now, Randy. I'll take the point
position of your squadron and direct operations. I'll relay course to
you as soon as we're in space."

"O.K., Steve," replied Randolph. "I'm ready to raise ship."

"I'll go up first. Form up around me at about five thousand miles. End
transmission!"

"End transmission!"

"All right, Tom," ordered Strong, "let's get out of here!"

The young cadet strapped himself into his acceleration chair, then
picked up the control panel intercom and began calling out orders
crisply.

"Stand by to raise ship! All stations check in!"

"Power deck standing by!" replied Astro from below.

"Radar bridge standing by!" acknowledged Roger over the intercom.

"Energize the cooling pumps!"

The whine of the mighty pumps began to fill the ship almost as quickly
as Astro acknowledged the order.

"Feed reactant!" snapped Strong, strapping himself in beside Tom.

A low-muted hiss joined the sound of the whining pumps as Tom opened the
valves. "Reactant feeding at D-9 rate, sir," he reported.

"Roger," called Strong into the intercom, "do we have a clear
trajectory?"

"Clear as space, skipper!" was Roger's breezy answer.

"All right, Tom," said Strong, "cut in take-off gyros."

The cadet closed the master switch on the control panel and the noise
from the power deck below began to build to an unbearable crescendo!

Watching