four, chart C for Charley. Corbett aboard spaceship _Space Knight_ in
quadrant four, chart C for Charley! Come in, Commander Walters! Come
in!"

Tom spun the dials on the audioceiver desperately, ranging over every
circuit and repeating his cry. "This is Cadet Corbett! I am being held
prisoner with Cadet Roger Manning aboard the spaceship _Space Knight_ in
space quadrant four, chart C for Charley...."

Suddenly the hum of the generators stopped and the glow of the tubes in
the audioceiver died. Without a second's hesitation, Tom spun around and
lunged for the door leading back to the control deck.

"They must have shut off the power," he decided. "When they didn't find
me down below, they guessed that I came this way."

He raced through the control deck and down the ladder to the starboard
companionway. If he could only get to the ship alongside!

He chided himself for not thinking of it before and darted toward the
air lock that coupled the two ships together in space.

He turned a corner in the companionway and saw the door to the coupling
chamber ahead. It was open. He dashed inside.

"Greetings, Corbett!" sneered Ross Miles. He stood just inside the
doorway, the ray gun leveled at Tom.

"We figured you'd get around to thinking about the other ship sooner or
later," said Quent behind him, jamming the ray gun in his back. "So we
just came here and waited for you."

"Go get the other one, Quent," said Ross. Jerking Tom sideways into the
coupling chamber, he rammed his gun into the curly-haired cadet's
stomach. "I'll get this guy fixed aboard the other ship, and then set
the firing chambers so they'll blow up."

"What are we going to do with Manning?" asked Quent.

"We'll figure that out later. Hurry up! Corbett probably called the
Solar Guard."

"That's right, I did, Miles," said Tom. "They're probably closing in on
you right now."

"Is that so?" snarled Quent. "Well, it's too bad you won't be alive to
say hello to them."

* * * * *

"I want every pound of thrust you have on that power deck, Astro,"
roared Commander Walters into the intercom. "We just received word from
a freighter that picked up an S O S from Tom aboard the _Space Knight_."

Steve Strong and Kit Barnard sat in the pilot and copilot's chairs on
the control deck of the _Polaris_ and watched the needle of the
accelerometer climb as Astro poured on the power in answer to Walters'
command.

"If I know