"Atom City Express now arriving on track two!" The voice boomed over the loud-speaker system; and as the long, gleaming line of monorail cars eased to a stop with a soft hissing of brakes, the three cadets of the Polaris unit moved eagerly in that direction.

"Atom City, here we come," cried Astro.

"We and a lot of others with the same idea," said Tom. And, in fact, there were only a few civilians in the crowd pressing toward the car doors. Uniforms predominated—the blue of the cadets, enlisted men in scarlet, even a few in the black and gold uniforms which identified the officers of the Solar Guard.

"Personally," whispered Tom to his friends, "the first thing I want to do at Atom City is take a long walk—somewhere where I won't see a single uniform."

"As for me," drawled Roger, "I'm going to find a stereo studio where they're showing a Liddy Tamal feature. I'll sit down in a front-row seat and just watch that girl act for about six hours."

He turned to Astro. "And how about you?"

"Why ... why ... I'll string along with you, Roger," said the cadet from Venus. "It's been a long time since I've seen a—a—"

Tom and Roger laughed.

"A what?" teased Tom .

"A—a—girl," sputtered Astro, blushing.

"I don't believe it," said Roger in mock surprise. "I never—"

"Come on," interrupted Tom. "Time to get aboard."

They hurried across the platform and entered the sleek car. Inside they found seats together and sank into the luxurious chairs.

Astro sighed gently, stretched out his long legs and closed his eyes blissfully for a few moments.

"Don't wake me till we get started," he said.

"We already have," returned Tom. "Take a look."

Astro's eyes popped open. He glanced through the clear crystal glass at the rapidly moving landscape.

"These express jobs move on supercushioned ball bearings," explained Tom. "You can't even feel it when you pull out of the station."

"Blast my jets!" marveled Astro. "I'd sure like to take a look at the power unit on this baby."

"Even on a vacation, all this guy can think about is power!" grumbled Roger.

"How about building up our own power," suggested Tom. "It's a long haul to Atom City. Let's get a bite to eat."

"O.K. with me, spaceboy!" Astro grinned. "I could swallow a whole steer!"

"That's a great idea, cadet," said a voice from behind them.

It came from a gray-haired man, neatly dressed in the black one-piece stylon suit currently in fashion, and with a wide red sash around his waist.

"Beg pardon, sir," said Tom, "were you speaking to us?"

"I certainly was," replied the stranger. "I'm asking you to be my guests at dinner. And while I may not be able to buy your friend a whole steer, I'll gladly get him a piece of one."

"Hey," said Astro, "do you think he means it?"

"He seems to," replied Tom. He turned to the stranger. "Thanks very much, sir, but don't think Astro was just kidding about his appetite."

"I'm sure he wasn't." The gray-haired man smiled, and came over and stretched out his hand. "Then it's a deal," he said. "My name's Joe Bernard."

"Bernard!" exclaimed Roger. He paled and glanced quickly at his two friends, but they were too busy looking over their new friend to notice.

"Glad to know you, sir," said Tom. "I'm Tom Corbett. This is Astro, from Venus. And over here is—"

"Roger's my name," the third cadet said quickly. "Won't you sit down, sir?"

"No use wasting time," said Bernard. "Let's go right into the dining car." The cadets were in no mood to argue with him. They picked up the small microphones beside their chairs and sent food orders to the kitchen; and by the time they were seated in the dining car, their orders were ready on the table.

Mr. Bernard, with a twinkle in his eye, watched them enjoy their food. In particular, he watched Astro.

"I warned you, sir," whispered Tom, as the Venusian went to work on his second steak.

"I wouldn't have missed this for anything," said Bernard. He smiled, lit a cigar of fine Mercurian leaf tobacco and settled back comfortably.

"And now," he said, "let me explain why I was so anxious to have dinner with you. I'm in the import-export business. Ship to Mars, mostly. But all my life I've wanted to be a spaceman."

"Well, what was the trouble, Mr. Bernard?" asked Roger.

The man in black sighed. "Couldn't take the acceleration, boys. Bad heart. I send out more than five hundred cargoes a year, to all parts of the solar system; but myself, I've never been more than a mile off the surface of the earth."

"It sure must be disappointing—to want to blast off, and know that you can't," said Tom.

"I tried, once," said Bernard, with a rueful smile. "Yup! I tried." He gazed thoughtfully out the window.

"When I was your age, about twenty, I wanted to get into Space Academy worse than anybody I'd ever met." He paused. "Except for one person. A boyhood buddy of mine—named Kenneth—"

"Excuse me, sir," cut in Roger quickly, "but I think we'd better get back to our car. With this big liberty in front of us, we need a lot of rest."

"But, Roger!" exclaimed Tom.

Bernard smiled. "I understand, Roger. Sometimes I forget that I'm an old man. And when you've already tasted the excitement of space travel, talk like mine must seem rather dull." He stood up and faced the three cadets. "It's been very pleasant, Corbett, Astro, Roger. Now run along and get your rest. I'll just sit here for a while and watch the scenery."

"Thank you, sir," said Tom, "for the dinner—your company—and everything," he finished lamely.

There was a chorus of good-byes and the boys returned to their car. But there was little conversation now. Gradually, the lights in the cars dimmed to permit sleep. But Tom kept listening to the subdued click of the monorail—and kept wondering. Finally Roger, sleeping next to him, wakened for a moment.

"Roger," said Tom, "I want to ask you something."

"Wait'll the mornin'," mumbled Roger. "Wanta sleep."

"The way you acted with Bernard," Tom persisted. "You ate his dinner and then acted like he was poison. Why was that, Roger?"

The other sat bolt upright. "Listen," he said. "Listen!" Then he slumped back in his chair and closed his eyes. "Lemme sleep, Corbett. Lemme sleep, I tell you." He turned his back and in a moment was making sounds of deep slumber, but Tom felt sure that Roger was not asleep—that he was wide awake, with something seriously bothering him.

Tom leaned back and gazed out over the passing plains and up into the deep black of space. The Moon was full, large and round. He could distinguish Mare Imbrium, the largest of Luna's flat plains visible from Earth, where men had built the great metropolis of Luna City. Farther out in the deep blackness, he could see Mars, glowing like a pale ruby. Before long he would be up there again. Before long he would be blasting off in the Polaris with Astro and with Roger—

Roger! Why had he acted so strangely at dinner?

Tom remembered the night he saw Roger in Galaxy Hall alone at night, and the sudden flash on the field a few days before when they had won the mercuryball game. Was there some reason behind his companion's strange actions? In vain, Tom racked his brain to find the answer. There had to be some explanation. Yet what could it possibly be? He tossed and turned and worried and finally—comfortable as the monorail car was—he fell asleep from sheer exhaustion.

Atom City! Built of the clear crystal mined so cheaply on Titan, moon of Saturn, Atom City had risen from a barren North American wasteland to become a show place of the universe. Here was the center of all space communications—a proud city of giant crystal buildings. Here had been developed the first slidewalks, air cars, three-dimensional stereos and hundreds of other ideas for better living.

And here at Atom City was the seat of the great Solar Alliance, housed in a structure which covered a quarter of a mile at its base and which towered three thousand noble feet into the sky.

The three cadets stepped out of the monorail and walked across the platform to a waiting air car—jet-powered, shaped like a teardrop and with a clear crystal top.

"We want the best hotel in town," said Astro grandly to the driver.

"And get this speed bug outa here in a hurry," Roger told him. "There's a lot we want to do."

The driver couldn't help smiling at the three cadets so obviously enjoying their first leave.

"We've got three top hotels," he said. "One's as good as the other. They're the Earth, the Mars and the Venus."

"The Earth," voted Tom.

"The Mars," shouted Roger.

"The Venus!" roared Astro.

"All right," said the driver with a laugh, "make up your minds."

"Which of 'em is nearest the center of the city?" Tom asked.

"The Mars."

"Then blast off for Mars!" ordered Tom, and the air car shot away from the station and moved up into the stream of expressway traffic fifty feet above the ground.

As the little car sped along the broad avenue, Tom remembered how often, as a boy, he'd envied the Space Cadets who'd come to his home town of New Chicago on leave. Now here he was—in uniform, with a three-day pass, and all of Atom City to enjoy it in.

A few minutes later the air car stopped in front of the Mars Hotel. The cadets saw the entrance loom before them—a huge opening, with ornate glass and crystal in many different colors.

They walked across the high-ceilinged lobby toward the desk. All around them, the columns that supported the ceiling were made of the clearest crystal. Their feet sank into soft, lustrous deep-pile rugs made of Venusian jungle grass.

The boys advanced toward the huge circular reception desk where a pretty girl with red hair waited to greet them.

"May I help you?" she asked. She flashed a dazzling smile.

"You're a lucky girl," said Roger. "It just so happens you can help me. We'll have dinner together—just the two of us—and then we'll go to the stereos. After which we'll—"

The girl shook her head sadly. "I can see your friend's got a bad case of rocket shock," she said to Tom.

"That's right," Tom admitted. "But if you'll give us a triple room, we'll make sure he doesn't disturb anybody."

"Ah," said Roger, "go blow your jets!"

"I have a nice selection of rooms here on photo-slides if you'd care to look at them," the girl suggested.

"How many rooms in this hotel, Beautiful?" asked Roger.

"Nearly two thousand," answered the girl.

"And you have photo-slides of all two thousand?"

"Why, yes," answered the girl. "Why do you ask?"

"You and Astro go take a walk, Corbett," said Roger with a grin. "I'll select our quarters!"

"You mean," asked the girl, a little flustered, "you want to look at all the slides?"

"Sure thing, Lovely!" said Roger with a lazy smile.

"But—but that would take three hours!"

"Exactly my idea!" said Roger.

"Just give us a nice room, Miss," said Tom, cutting in. "And please excuse Manning. He's so smart, he gets a little dizzy now and then. Have to take him over to a corner and revive him." He glanced at Astro, who picked Roger up in his arms and walked away with him as though he were a baby.

"Come on, you space Romeo!" said Astro.

"Hey—ouch—hey—lemme go, ya big ape. You're killing your best friend!" Roger twisted around in Astro's viselike grasp, to no avail.

"Space fever," explained Tom. "He'll be O.K. soon."

"I think I understand," said the girl with a nervous smile.

She handed Tom a small flashlight. "Here's your photoelectric light key for room 2305 F. That's on the two hundred thirtieth floor."

Tom took the light key and turned toward the slidestairs where Astro was holding Roger firmly, despite his frantic squirming.

"Hey, Tom," cried Roger, "tell this Venusian ape to let me go!"

"Promise to behave yourself?" asked Tom.

"We came here to have fun, didn't we?" demanded Roger.

"That doesn't mean getting thrown out of the hotel because you've got to make passes at every beautiful girl."

"What's the matter with beautiful girls?" growled Roger. "They're official equipment, like a radar scanner. You can't get along without them!"

Tom and Astro looked at each other and burst out laughing.

"Come on, you jerk," said Astro, "let's get washed up. I wanta take a walk and get something to eat. I'm hungry again!"

An hour later, showered and dressed in fresh uniforms, the Polaris crew began a tour of the city. They went to the zoo and saw dinosaurs, a tyrannosaurus, and many other monsters extinct on Earth millions of years ago, but still breeding in the jungles of Tara. They visited the council chamber of the Solar Alliance where delegates from the major planets and from the larger satellites, such as Titan of Saturn, Ganymede of Jupiter, and Luna of Earth made the laws for the tri-planetary league. The boys walked through the long halls of the Alliance building, looking at the great documents which had unified the solar system.

They reverently inspected original documents of the Universal Bill of Rights and the Solar Constitution, which guaranteed basic freedoms of speech, press, religion, peaceful assembly and representative government. And even brash, irrepressible Roger Manning was awestruck as they tiptoed into the great Chamber of the Galactic Court, where the supreme judicial body of the entire universe sat in solemn dignity.

Later, the boys visited the Plaza de Olympia—a huge fountain, filled with water taken from the Martian Canals, the lakes of Venus and the oceans of Earth, and ringed by a hundred large statues, each one symbolizing a step in mankind's march through space.

But then, for the Space Cadets, came the greatest thrill of all—a trip through the mighty Hall of Science, at once a museum of past progress and a laboratory for the development of future wonders.

Thousands of experiments were being conducted within this crystal palace, and as Space Cadets, the boys were allowed to witness a few of them. They watched a project which sought to harness the solar rays more effectively; another which aimed to create a new type of fertilizer for Mars, so people of that planet would be able to grow their own food in their arid deserts instead of importing it all from other worlds. Other scientists were trying to adapt Venusian jungle plants to grow on other planets with a low oxygen supply; while still others, in the medical field, sought for a universal antibody to combat all diseases.

Evening finally came and with it time for fun and entertainment. Tired and leg weary, the cadets stepped on a slidewalk and allowed themselves to be carried to a huge restaurant in the heart of Atom City.

"Food," exulted Astro as the crystal doors swung open before them. "Smell it! Real, honest-to-gosh food!" He rushed for a table.

"Hold it, Astro," shouted Tom. "Take it easy."

"Yeah," added Roger. "It's been five hours since your last meal—not five weeks!"

"Meal!" snorted the Venusian cadet. "Call four spaceburgers a meal? And anyway, it's been six hours, not five."

Laughing, Tom and Roger followed their friend inside. Luckily, they found a table not far from the door, where Astro grabbed the microphone and ordered his usual tremendous dinner.

The three boys ate hungrily as course after course appeared on the middle of the table, via the direct shaft from the kitchen. So absorbed was Manning that he did not notice the approach of a tall dark young man of about his own age, dressed in the red-brown uniform of the Passenger Space Service. But the young man, who wore a captain's high-billed hat, suddenly caught sight of Roger.

"Manning," he called, "what brings you here?"

"Al James!" cried Roger and quickly got up to shake hands. "Of all the guys in the universe to show up! Sit down and have a bite with us."

The space skipper sat down. Roger introduced him to Tom and Astro. There was a round of small talk.

"Whatever made you become a Space Cadet, Roger?" asked James finally.

"Oh, you know how it is," said Roger. "You can get used to anything."

Astro almost choked on a mouthful of food. He shot a glance at Tom, who shook his head as though warning him not to speak.

James grinned broadly. "I remember how you used to talk back home. The Space Cadets were a bunch of tin soldiers trying to feel important. The Academy was a lot of space gas. I guess, now, you've changed your mind."

"Maybe I have," said Roger. He glanced uneasily at his two friends, but they pretended to be busy eating. "Maybe I have." Roger's eyes narrowed, his voice became a lazy drawl. "At that it's better'n being a man in a monkey suit, with nothing to do but impress the passengers and order around the crew."

"Wait a minute," said James. "What kind of a crack is that?"

"No crack at all. Just the way I feel about you passenger gents who don't know a rocket tube from a ray-gun nozzle."

"Look, Manning," returned James. "No need to get sore, just because you couldn't do any better than the Space Cadets."

"Blast off," shouted Roger, "before I fuse your jets."

Tom spoke up. "I think you'd better go, Captain."

"I've got six men outside," sneered the other. "I'll go when I'm ready."

"You're ready now," spoke up Astro. He stood up to his full height. "We don't want any trouble," the cadet from Venus said, "but we're not braking our jets to get away from it, either."

James took a good look at Astro's powerful frame. Without another word he walked away.

Tom shook his head. "That pal of yours is a real Space Cadet fan, isn't he, Roger?"

"Yeah," said Astro. "Just like Manning is himself."

"Look," said Roger. "Look, you guys—" He hesitated, as though intending to say something more, but then he turned back to his dinner. "Go on—finish your food," he growled. He bent over his plate and ate without lifting his eyes. And not another word was spoken at the table until a young man approached, carrying a portable teleceiver screen.

"Pardon me," he said. "Is one of you Cadet Tom Corbett?"

"Why—I am," acknowledged Tom.

"There's a call for you. Seems they've been trying to reach you all over Atom City." He placed the teleceiver screen on the table, plugged it into a floor socket and set the dials.

"Hope's there's nothing wrong at home," said Tom to his friends. "My last letter from Mom said Billy was messing around with a portable atom reactor and she was afraid he might blow himself up."

A picture began to take shape on the screen. "Migosh," said Astro. "It's Captain Strong."

"It certainly is," said the captain's image. "Having dinner, eh, boys? Ummmm—those baked shrimps look good."

"They're terrific," said Astro. "Wish you were here."

"Wish you could stay there," said Captain Strong.

"Oh, no!" moaned Astro. "Don't tell me!"

"Sorry, boys," came the voice from the teleceiver. "But that's it. You've got to return to the Academy immediately. The whole cadet corps has been ordered into space for special maneuvers. We blast off tomorrow morning at six hundred."

"But, sir," objected Tom, "we can't get a monorail until morning!"

"This is an official order, Corbett. So you have priority over all civilian transportation." The Solar Guard captain smiled. "I've tied up a whole bank of teleceivers in Atom City searching for you. Get back to Space Academy fast—commandeer an air car if you must, but be here by six hundred hours!" The captain waved a cheery good-bye and the screen went dark.

"Space maneuvers," breathed Astro. "The real thing."

"Yeah," agreed Tom. "Here we go!"

"Our first hop into deep space!" said Roger. "Let's get out of here!"