Charles Brett swaggered into the control room of the electronics building. Commander Walters, Captain Strong, and Kit Barnard looked up from their study of the reports the chief engineer had handed them.

"What are you doing here, Brett?" demanded Walters. "I thought you had blasted out of here long ago."

"I'm leaving as soon as we sign the contracts for hauling the crystal, Commander," said Brett.

"Contracts!" exploded Strong. "Why, man, do you realize that this satellite is about to die? If we don't find out what's wrong with the screens, there won't be any crystal mined here for the next ten years."

Brett shook his head and smiled. "That's all right with me too," he said. "The contracts call for either party to satisfy the other should either party fail to fulfill the contractual agreements. In other words, Strong, I get paid for making the trip out to Titan, whether you have crystal to haul or not."

"Why, you dirty—" snarled Strong.

"Just a moment, Steve," Walters interrupted sharply. "Brett's right. We had no way of knowing that this situation would arise, or grow worse than it was in the beginning. Brett went to a great deal of expense to enter the race and win it. If he insists that the Solar Guard abide by the contract, there's nothing we can do but pay."

"It won't be too bad, Commander Walters," said Brett. "I have my ship loaded with crystal now, and if you'll just sign the contracts, I can deliver one cargo of crystal to Atom City before Titan is abandoned."

"Wait a minute," cried Strong. "Who gave you the right to load crystal before signing the contract?"

"I assumed the right, Captain Strong," replied Brett smoothly. "My ship won the race, didn't it? Why shouldn't I start work right away?"

"Well, that's beside the point now, anyway," Walters said. "We may need your ship to take miners and their families to Ganymede or Mars, Brett. Never mind the crystal. One load won't mean very much, anyway."

"No, thank you," growled Brett. "I don't haul any miners in my ship. The contracts call for crystal and that's all."

"I'm ordering you to take those people, Brett," said Walters coldly. "This is an emergency."

"Order all you want," snapped Brett. "Look at your space code book, section four, paragraph six. My rights are fully protected from high-handed orders issued by men like you who think they're bigger than the rest of the people."

Walters flushed angrily. "Get out!" he roared.

"Not till you sign that contract," Brett persisted. "And if I don't leave with a signed contract in my pocket, I'll have you up before the Solar Alliance Council on charges of fraud. You haven't got a leg to stand on and you know it. Now sign that contract."

Abruptly, Walters turned to an enlisted spaceman and instructed him to get his brief case from the Polaris, then deliberately turning his back on Brett, continued his study of the report. Strong and Kit Barnard watched Brett with narrowed eyes as the arrogant company owner crossed to the other side of the room and sat down.

"You know something, Steve," said Kit quietly. "Back at the Academy, I failed to register a protest about someone dumping impure reactant into my feeders."

"What about it?" asked Strong.

"I'd like to register that protest now."

"Now?" Steve looked at him, a frown on his face. "Why now?"

"For one thing, Brett couldn't blast off until there was an investigation."

"You might have something there, Kit," replied Strong with a smile. "And since Brett won the race under such—er—mysterious circumstances, I'd suggest an investigation of the black ship as well, eh?"

Kit grinned. "Shall I make that a formal request?"

"Right now, if you like."

Kit turned to face Commander Walters. "Commander," he announced, "I would like to register a formal protest with regard to the race."

Walters glanced up. "Race?" he growled. "What the devil are you talking about, Kit?"

"Captain Barnard seems to think that Mr. Brett's ship might have used equipment that was not standard, sir," Strong explained. "In addition, his own ship was sabotaged during the time trials."

Walters looked at Strong and then at Kit Barnard, unable to understand. "What's happened to you two? Bringing up a thing like that at this time. Have you lost your senses?"

"No, sir," replied Kit. "But I believe that if a formal investigation was started, the Solar Guard would be within its legal rights to delay signing the contracts until such investigation was completed."

Walters grinned broadly. "Of course! Of course!"

Brett jumped up and stormed across the room. "You can't get away with this, Walters!" he shouted. "I won this race fairly and squarely. You have to sign that contract."

"Mr. Brett," said Walters coldly, "under the circumstances, I don't have to do a space-blasted thing." He turned to Kit. "Is this a formal request for an investigation, Kit?" He was smiling.

"It is, sir."

"Very well," said Walters, turning to Brett. "Mr. Brett, in the presence of two witnesses, I refuse to sign the contracts as a result of serious charges brought against you by one of the participating entrants. You will be notified of the time and place of the hearing on these charges."

Brett's face turned livid. "You can't do this to me!"

Walters turned to one of the enlisted guardsmen. "Escort Mr. Brett from the room," he ordered.

A tall, husky spaceman unlimbered his paralo-ray rifle and nudged Brett from the room. "I'll get even with you, Walters, if it's the last thing I do," he screamed.

"You make another threat like that to a Solar Guard officer," growled the enlisted spaceman, "and it'll be the last thing you do."

As the door closed, Walters, Strong, and Kit laughed out loud. A few seconds later, as the three men returned to their study of the report, there was a distant rumble, followed quickly by the shock wave of a tremendous explosion. Walters, Strong, and Kit and everyone in the room were thrown to the floor violently.

"By the craters of Luna," yelled Strong, "what was that?"

"One of the smaller screens has given way, sir!" yelled the chief electronic engineer after a quick glance at the giant control board. "Number seven."

Walters struggled to his feet. "Where is it?" he demanded.

Strong and Kit got to their feet and crowded around the commander as the engineer pointed out the section on the huge map hanging on the wall.

"Here it is, sir," he said. "Sector twelve."

"Has that area been evacuated yet?" asked Strong.

"I don't know, sir," replied the engineer. "Captain Howard was in charge of all evacuation operations."

Walters spun around. "Get Howard, Steve. Find out if that part of the city has been cleared," he ordered and then turned to Kit. "You, Kit, take the Space Marines and round up every spare oxygen mask you can find and get it over to that section right away. I'll meet you here"—he placed his finger on the map—"with every jet car I can find. No telling how many people are still there and we have to get them out."

Almost immediately the wailing of emergency sirens could be heard spreading the alarm over the city. At the spaceport, where the citizens were waiting to be taken off the satellite, small groups began to charge toward the loading ships in a frenzy of fear. Since Titan had been colonized, there had never been a single occasion where the sirens had warned of the failure of the screens. There had been many tests, especially for the school-age children and the miners working far below the surface of the satellite, but this was the first time the sirens howled a real warning of danger and death.

Strong raced back to the control tower of the spaceport in a jet car and burst into the room where the captain was still asleep on the couch. Strong shook him violently.

"Wake up, Joe!" he cried. "Come on. Wake up."

"Uh—ahhh? What's the—?" Howard sat up and blinked his eyes. "Steve, what's going on?"

"The screen at sector twelve has collapsed. How many people are still in there?"

"Collapsed! Sector twelve?" Howard, still groggy with sleep, dumbly repeated what Strong had said.

Strong drew back his hand and slapped him across the face. "Come out of it, Joe!" he barked.

Howard reeled back and then sat up, fully awake.

"What—what did you say?" he stammered.

"Sector twelve has gone," Strong repeated. "How many people are left there?"

"We haven't even begun operations there yet," Howard replied grimly. "How long have I been asleep?"

"A couple of hours."

"Then there's still time."

"What do you mean?"

"Just before I folded, I ordered the evacuation crews to start working on sector eleven. They should be finished now and just about starting on twelve. If they have, we have a good chance of saving everyone."

"Let's go."

The two men raced out of the control tower to the jet car and roared through the desolate streets of the city. All around them commandeered jet cars raced toward the critical area. Commander Walters stood in the middle of an intersection on the main road to sector twelve, waving his arms and shouting orders to the enlisted guardsmen and volunteer miners that had raced back into the city to help. On the sidewalk, enlisted guardsmen handed out extra oxygen masks to the men who would search the area for anyone who might not have gotten out before the screen exploded. The main evacuation force that had been under Howard's supervision had already moved in but there was still a large area to cover.

"We'll split up into six sections!" roared Walters, standing on top of a jet car. "Go down every street and alley, and make a house-to-house search. Cover every square inch of the sector. If we lose one life, we will have failed. Move out!"

With Strong, Kit, Howard, Walters, and other officers of the Solar Guard in the lead, the grim lines of men separated into smaller groups and started their march through the deserted city. The swirling gas already was down to within a hundred feet of the street level. When it dropped to the surface, each man knew there would be little hope for anyone remaining alive without oxygen masks.

Every room of every house and building was searched, as over all, the deadly swirling gas dropped lower and lower and the pressure of the oxygen was dissipated.

Once, Strong broke open the door to a cheap rooming house and raced through it searching each room. He found no one, but something made him go back through the first-floor rooms again. Under a bed in a room at the end of the hall he found a young boy huddled with his dog, wide-eyed with fear. Such incidents were repeated over and over as the searchers came upon sleeping miners, sick mothers and children, elderly couples that were unable to move. Each time they were taken outside to a jet car where masks were strapped over their faces, and then driven to the spaceport. And, all the while, the deadly methane ammonia gas dropped lower and lower until it was within ten feet of the ground.

There were only a few buildings left to search now. The lines of the men had reached the open grassy areas surrounding the city proper, and as they collected in groups and exchanged information, Walters gathered them together.

"You've done a fine job, all of you," he said. "I don't think there's a living thing left in this entire sector. All volunteers and the first four squads of enlisted guardsmen and second detachment of Space Marines return to the spaceport and prepare to abandon Titan. Give all the aid to the officer in charge that you can. Again, I want to thank you for your help."

As the group of men broke up and began drifting away, Walters hurried over to Strong and Kit Barnard. "Steve," he said, "I want you to supervise the evacuation at the spaceport. Since this screen has blown up, those poor people are frightened out of their wits. And they have a right to be. If a major screen blew instead of a small one, we really would be in trouble."

"Very well, sir," replied Strong. "Come on, Kit, you might as well blast off with a load of children."

"Sure thing."

"Just a minute," Walters interrupted. "I would consider it a service, Kit, if you would send your young assistant back with your ship and you stick around until we get all the people safely off."

"Anything I can do to help, sir," replied Kit.

At that moment a tall enlisted spaceman walked up to Walters and saluted sharply. Walters noticed the stripes on his sleeve and his young-looking face. He couldn't remember ever seeing such a young master sergeant.

"Captain Howard asked me to make my report to you, sir," said the guardsman.

"Very well, sergeant," said Walters.

The young spaceman made a detailed report of his search through sectors eleven and twelve. While he spoke, Strong kept looking at him, puzzled. When the guardsman had finished, Strong asked, "Don't I know you from somewhere, Sergeant?"

The guardsman smiled. "You sure do, Captain Strong. My name's Morgan, sir. I was a cadet with Tom Corbett and Astro, sir, but I washed out. So I joined the enlisted guard."

"Congratulations, Sergeant," said Walters. "You're the youngest top kick I've ever seen." He turned to Strong. "Apparently we slipped up, Steve, letting this chap get out of the Academy so he could make a name for himself in the enlisted ranks."

"Thank you, sir," replied Morgan, blushing with pride.

"Have you seen the cadets, by any chance, Sergeant?" asked Strong. "They're both here on Titan with me."

"Oh, yes, sir," said Morgan. "I saw them some time ago."

"Where?"

"A few blocks closer to the heart of town," said Morgan, pointing back down the avenue. "We were just starting in on sector eleven and I saw them coming out of a restaurant."

"Funny they haven't returned," commented Walters. "And what would they be doing down there?"

Strong's forehead creased into a frown of worry. "Sir, I wonder if you'd allow me a half hour or so to look for them?" he asked. "If they were anywhere near this section when the screen collapsed, they could have been injured by the sudden release of pressure."

"They had masks, sir," said Morgan. "I gave them a couple myself."

Walters thought a moment. "It's just possible they might have been injured in some way," he mused. "Go ahead, Steve. If you don't find them, and they don't show up at the spaceport, we'll organize a full search."

"Thank you, sir," said Strong. "You come along with me, Sergeant."

Adjusting their oxygen masks, Captain Strong and Sergeant Morgan strode down the street through the swirling mist of deadly methane ammonia to begin their search for Tom and Astro.