"I don't know what you're talking about!"

Shouting angrily, Barret sat in one of the pilot's chairs, flanked by Roger and Astro, while Connel and Tom stood in front of him firing questions.

"Barret," said Connel, "I have enough evidence on you now to send you to a prison asteroid for ten years at least!"

"On what charge?" demanded the young man.

"Trying to kill an officer of the Solar Guard."

"Where is your proof?" demanded Barret.

"Right there!" snorted Major Connel, pointing to the sleeping figure of Professor Hemmingwell.

"What do you mean?" demanded Barret.

"He'll swear that you deliberately sent this ship into full drive while I was out on the hull checking the rings."

"He can't," protested Barret. "He was on the bridge! He couldn't have seen a thing!"

Tom shook his head gently. "Barret, after what you've done to his ship and the projectile operation," he said, "Hemmingwell will swear to anything."

"It's a frame-up!" shouted Barret.

"And what do you think you did to us?" snarled Roger.

Barret flushed and turned away. "You can't scare me," he muttered. "Go ahead. Let him swear to whatever he wants."

Connel stepped back grimly and turned to Astro and Roger. "All right, boys," he said. "Take him below and see if you can't get some different answers out of him." The hardened spaceman turned his back and walked to the viewport.

"Why, you dirty space rat!" screamed Barret. "You wouldn't dare!"

"Oh, wouldn't he!" retorted Roger. "Listen, pal, he figures we owe you plenty for what you did to us, and he's just giving us a chance to pay you back!" He faced Barret grimly. "Mister, you're going to get the works! Come on, Astro!"

As the giant Venusian advanced on Barret, the man shrank back in his chair, eyes widening in sudden fear. When Astro stretched out his huge hand and grabbed him by the front of his jacket, he screamed in fright.

"All right, all right!" he cried out. "I'll talk! Devers did it! He made me do it! He's responsible for the whole thing!"

"Turn on that audiograph, Corbett!" shouted Connel.

Tom snapped on the machine and brought the microphone over to Barret, holding it in front of his trembling mouth.

"All right, talk!" Connel growled. "And tell it all."

Barret had hardly uttered the first stumbling words when Roger let out a shout of alarm. "Hey! The scanner!" he cried.

They all turned to the teleceiver screen. To their horror, they saw a menacing shape blasting toward them. They recognized it instantly—a space torpedo!

Astro dove through the power-deck hatch while Roger raced for the radar-bridge ladder. Tom hurled himself into the copilot's chair, and with Connel beside him in the command position, he waited for Astro to supply power. Suddenly the ship trembled violently and then shot forward as, far below, the jet exhausts screamed under the full thrust of all the atomic reactors. Tom rode the controls hard and kept his eye on the scanner screen.

"It's a magnetic gyrofish!" he cried as he saw the torpedo curve after them. "Roger, can you plot her for me?"

"Working on it now, Tom!" yelled Roger over the intercom.

"How in blazes did that thing get out here?" muttered Connel.

"We'll have to worry about that later, I'm afraid, sir," replied Tom. "We're going to have our hands full getting away from her. With that magnetic warhead, she'll follow us all over space unless we can throw her off."

"Which will take some doing!" grunted Connel, frowning in deep concern.

"Hey, Tom!" Roger's voice called over the intercom. "It's blasting on maximum thrust now. We have a pretty good chance. Use that idea we worked out. Make a series of left turns and always on the up-plane of the ecliptic!"

"Right!" said Tom, clutching the master manual-control lever and beginning to fly the giant ship through space by "feel."

"What in blazes are you doing, Corbett?" shouted Connel in sudden alarm.

"Just hang on and watch, sir," replied Tom, keeping his eyes on the scanner where he could see the space torpedo trailing them. Over and over, Tom kept slamming the ship into sharp left turns, while the torpedo followed in an ever-narrowing circle.

"All right, Tom!" yelled Roger again. "Give it the same thing on the right and the down-plane of the ecliptic!"

"Check!" answered Tom, reversing his controls and sending the ship corkscrewing through space on an opposite course.

Connel grabbed the arms of his chair and gasped, "You kids are space happy!"

"Those gyros are so perfect, sir," said Tom, working the controls quickly and smoothly, "that the only way you can throw them off balance is to confuse them."

"Confuse them!" exclaimed Connel.

"Yes, sir," said Tom. "It's a theory Roger and I worked out together. No gyro is perfect, and if you can get it bouncing back and forth in extreme turns, it will be thrown out of balance. Then all we have to do is make the torpedo miss once and it won't come back."

"Heaven help us all!" was Connel's groaning reply.

"On the ball, Tom!" cried Roger. "She's closing in on us!"

"I see her," replied Tom calmly. "Hang on, everybody. I'm going to turn this ship inside out!"

Jerking the controls, Tom threw the ship into a mad, whirling spin, subjecting the vessel to the most severe strain tests it would ever undergo. The hull groaned and creaked, and badly fitted equipment tore loose and clattered across the deck. Suddenly the young cadet leveled the ship.

"Nose braking rockets, Astro!" he called.

"Braking rockets, aye!" acknowledged the Venusian over the intercom.

On the power deck, Astro jammed the forward drive closed and slammed open the nose rockets. The ship trembled, bucked, and finally came to a shuddering stop before it started a reverse course, accelerating quickly.

"Here it comes!" yelled Roger.

As Connel and Tom watched tensely, the space torpedo loomed large and menacing on the scanner, and then, as they held their breaths, it whistled past the silvery hull of the ship, with less than two feet to spare!

Sighing deeply, Tom brought the ship back to level flight. "We're O.K. now, sir," he said. "Her gyros are out. She won't come back."

"By the craters of Luna!" Connel suddenly exploded. "The Solar Guard spends a fortune to develop a foolproof space torpedo and two hot-shot cadets come along and get away from the blasted thing! Why haven't you told this to anyone before?"

"Why—er—" stammered Tom, "we've never had the chance to prove it, sir."

Behind them, the power-deck hatch suddenly opened and Astro stepped in. "Nice work, Tom!" he called.

"And as for you, you Venusian ape," roared Connel, "don't you realize that you can blow a reactor tube by throwing so much power into a ship without energizing the cooling pumps first?"

Astro smiled. "Not if you open the by-pass, sir," he said, "and feed directly off the pump reservoir. The gas cools the tube and at the same time expands itself and adds to the power thrust."

At Astro's easy reply Connel could only stand openmouthed in amazement. Again, one of the three cadets of the Polaris unit had developed a revolutionary procedure that even top rocket scientists would be proud to call their own.

Winking at Tom, Astro turned away and suddenly noticed Barret sprawled on the deck, unconscious.

"What happened to him?" asked the big Venusian.

"Oh, I forgot all about him," said Tom. "Guess he didn't get into an acceleration chair in time. Better get some more water."

"We haven't time for him now!" snapped Connel. "Strap him in good and tight. We've got to find out where that torpedo came from."

As though in answer to the major's order, there was a sudden call over the ship's intercom.

"Radar bridge to control deck, check in!" There was a note of alarm in Roger's voice.

Tom jumped to the control panel to reply.

"Control deck, aye!" he snapped into the microphone.

"There's a spaceship to starboard!" called Roger. "Distance twenty miles, fifteen degrees up on the plane of the ecliptic. And I swear she's maneuvering to fire another torpedo!"

"Stand by action stations!" roared Connel, diving into his chair before the control panel. Tom strapped in next to him, while Astro made a headlong dash for the power deck.

"Yes!" shouted Roger. "She's fired a torpedo!"

"Raise her! Raise her!" bellowed Connel. "Tell them who we are!" He turned to Tom. "Go into your act, Corbett," he said, "and make it good!"

As Tom manipulated the controls again, the silver ship plunged through space, turning and gyrating in the same series of maneuvers it had performed to escape the first torpedo. But this time the distance separating them was not as great and the torpedo closed in quickly.

"Can't you raise that ship yet, Manning?" Connel roared into the intercom.

"I just have, sir," replied Roger in a strained voice. "But it's—"

"Let me talk to that lame brain of a skipper," interrupted Connel. "By the stars, I'll teach him to—"

"It's no use, Connel," said a gruff voice over the control-deck loud-speaker. "Even if you duck this torpedo, I've got ten more!"

"Who is this?" roared Connel.

"Don't you know, Connel? Why, I'm surprised!"

The teleceiver screen glowed into life and Tom and Connel stared in horror as they recognized the images of three men. The one in the foreground smiled mockingly and said, "Remember me, Connel?"

"Devers!" Connel roared.

"And the other two behind him—" stuttered Tom. "Cag and Monty!"

"Why, you dirty space crawler," cried Connel, "I'll get you if it's the last thing I do!"