"Yes, sir," replied the officer. He rammed the accelerator to the floor and the small truck blasted through the streets as though shot out of cannon.

In a few minutes the truck screamed to a halt in front of the building and Strong leaped toward the door, followed closely by Sergeant Morgan and the s.p.a.ce Marine lieutenant.

Strong found Walters before the telemetering board waiting impatiently for some figures Dr. Joan Dale had sent him to be a.n.a.lyzed and evaluated. He spun around when Strong entered the room at a dead run.

"Steve!" he exclaimed. "What's the matter? Anything happen to the cadets?"

"We didn't find them, sir, but we did find something else. We--" Before Strong could finish, the calculator began pouring out its answers.

"Excuse me, Steve! These figures could tell us why the screens are failing."

"But I know why they're failing, sir!" shouted Strong.

"You know what?" exclaimed Walters.

As all the men in the room stared at him, Strong hurriedly told the commanding officer what he had found, concluding, "I think the room I stumbled into was used as a repair shop. But it was gas-free and pure oxygen was coming out of the pipe I described."

"I see," said Walters grimly. "Let me check that against these figures."

He turned to the calculator and with the a.s.sistance of Joe Howard, Kit Barnard, and the chief electronics engineer began studying the figures.

Strong paced up and down nervously. The faces of the technicians in the room clearly showed the strain they had been under the past few days.

And when they heard the startling news Strong had delivered, there wasn't one who didn't feel his fingers tighten into fists at Brett and Miles' selfishness.

Walters straightened up and glanced at the faces of the men around him.

"Well, gentlemen," he said. "I think the figures speak for themselves."

There was a murmur of agreement. Walters turned back to Strong. "Those figures prove conclusively that what you say is true. It is impossible for the screens to collapse except from a vital leak--exactly such a leak as you have described."

Walters turned and began to snap orders to the men around him. "I want every available man sent out on the double. I want every inch of that area searched for an opening to a mine shaft or anything that leads underground. Take half the men off the s.p.a.ceport detail."

"Shall we continue evacuation operations for the miners and their families?" asked the young s.p.a.ce Marine lieutenant. "There is quite a force of men out there that could be used in the search."

"What do you think, Steve? Should we take off the guardsmen and suspend evacuation in the hope that we can find that leak?"

"I would say yes, Commander," said Strong. "Your figures and those Dr.

Dale sent you point to a leak of this nature."

"Very well, Lieutenant," said Walters. "Order every man to the area and begin search operations immediately. I want that leak found--and found fast! And I want Charles Brett and Quent Miles arrested at once!"

Tom and Astro bent over the lead boxes again and heaved them to their shoulders. A quick glance showed them that Miles had not followed them to the floor of the cavern as he had done before, but had remained on guard on the balcony.

As they struggled to lift the boxes to their shoulders, Tom whispered out of the side of his mouth, "I know how we can get out of here, Astro."

"How?"

"Since Brett is staying on the ship for this trip, Miles is going to have trouble watching both of us."

"Yeah, I know," muttered Astro. "Want me to jump him?"

"No," Tom growled. "Miles has been trailing us through the tunnel by twenty to thirty feet each trip. When we pa.s.s that spot where the light is, you drop your box. He'll be watching you then and that will give me a chance to grab that b.o.o.by trap you took apart, remember?"

"Yeah!"

"O.K. Now remember, when I give you the word, you drop your box on the right-hand side of the tunnel."

"Hurry up down there!" yelled Miles from the balcony. "We haven't got all night."

"Keep your shirt on, buster," growled Astro. "We're tired."

The two cadets balanced the heavy lead boxes on their shoulders, and, with Tom leading the way, climbed up the stairs past Miles and started up the tunnel in front of the black-suited s.p.a.ceman.

They walked slowly, side by side, and as before, Miles stayed a good twenty paces behind them. As they neared the light where they knew the explosive charge would be, Tom began slowing his pace.

"Come on, get going, Corbett!" Miles yelled.

"He's tired," said Astro. "Leave him alone."

"What are you, his protector?" snarled Miles. "Get going, I said."

"O.K.," said Tom, struggling forward.

They came closer and closer to the light. Tom glanced at Astro and winked. Astro winked back and braced himself to fake the accident.

As closely as Tom could remember, Astro had tossed the charge to one side about ten feet beyond the light. If he knew exactly where it was, he could fall forward on top of it and stuff it in his tunic. He tried to recreate the scene as it happened. They pa.s.sed under the light. One step ... two steps ... three steps.... "Now, Astro," Tom whispered.

The big cadet lunged to one side, dropping the heavy box to the floor.

At the same time, Tom dropped his box and lunged forward, arms outstretched, feeling along the floor for the precious explosives.

Miles ran up quickly, ray gun c.o.c.ked and ready.

"Get up!" he shouted. "Get up or I'll freeze you both and leave you here!"

Tom and Astro struggled to their feet. They lifted the heavy boxes to their shoulders and started down the tunnel again.

When Astro dared a glance at Tom, he saw his unit mate grin and wink at him. Astro winked back. Suddenly it seemed that the heavy lead box was as light as air!

CHAPTER 17

The streets of Olympia echoed to the thunderous roar of jet trucks and jet cars racing to sector twelve. Miners, Solar Guardsmen, and s.p.a.ce Marines jammed the vehicles, their faces grim with determination as they prepared for an all-out attempt to prevent the death of the colony.

Walters, Strong, and Kit Barnard sat behind Blake, the s.p.a.ce Marine lieutenant, and Sergeant Morgan as they rocketed through the streets.

There was little conversation, each man thinking bitterly of Charles Brett and Quent Miles. Walters had already foreseen the possibility of trouble with emotional miners and had ordered Blake to be personally responsible for the safety of Miles and Brett when they were arrested.