you some ideas."

"Thanks," replied Connel, also forgetting the hot exchange of a few minutes before. He stood up. "I'll take the Polaris, Commander. She's the fastest ship available with automatic controls for a solo hop."

"She's been stripped of her reactant pile, Major," said Strong. "It'll take a good eighteen hours to soup her up again."

"I'll take care of it," said Connel. "Are there any specific orders, Commander?"

"Use your own judgment, Lou," said Walters. "You know what we want and how far to go to get it. If you learn anything, we'll start a full-scale investigation. If not, we'll forget the whole matter and no one will get hurt."

"And the Solar Guard won't get a reputation of being nosy," added Strong.

Connel nodded. "I'll take care of it." He shook hands all around, coming to Sykes last. "Sorry I lost my temper, Professor," he said gruffly.

"Forget it, Major." Sykes smiled. He really admired the gruff spaceman.

The thick-set senior officer came to smart attention, saluted crisply, turned, and left the office. For the time being, the mysterious trouble on Venus was his responsibility.

"Atom City express leaving on Track Four!"

A metallic voice boomed over the station loud-speaker, as last-minute passengers boarded the long line of gleaming white monorail cars, hanging from a single overhead steel rail. In the open doorway of one of the end cars, a conductor lifted his arm, then paused and waited patiently as three Space Cadets raced down the stairs and along the platform in a headlong dash for the train. They piled inside, almost one on top of the other.

"Thanks for waiting, sir," gasped Tom Corbett.

"Not at all, Cadet," said the conductor. "I couldn't let you waste your leave waiting for another train."

The elderly man flipped a switch in the narrow vestibule and the door closed with a soft hiss of air. He inserted a light key into a near-by socket and twisted it gently, completing a circuit that flashed the "go" light in the engineer's cab. Almost immediately, the monorail train eased forward, suspended on the overhead rail. By the time the last building of Space Academy flashed past, the train was rolling along at full speed on its dash across the plains to Atom City.

The ride to the great metropolis of the North American continent was filled with excitement and anticipation for the three members of the Polaris crew. The cars were crowded with cadets on leave, and while there was a lot of joking and horseplay, the few civilian passengers were impressed with the gentlemanly bearing of the young spacemen. Tom and Roger finally settled down to read the latest magazines supplied by the monorail company. But Astro headed for the dining car where he attracted a great deal of attention by his order of a dozen eggs, followed by two orders of waffles and a full quart of milk. Finally, when the dining-car steward called a halt, because it was closing time, Astro made his way back to Tom and Roger with a plastic bag of French fried potatoes, and the three boys sat, munching them happily. The countryside flashed by in a blur of summer color as the train roared on at a speed of two hundred miles an hour.

A few hours and four bags of potatoes later, Astro yawned and stretched his enormous arms, nearly poking Roger in the eye.

"Hey, ya big ape!" growled Roger. "Watch the eye!"

"You'd never miss it, Manning," said Astro. "Just use your radar."

"Never mind, I like this eye just the way it is."

"We're almost there," called Tom. He pointed out the crystal window and they could see the high peaks of the Rocky Mountain range looming ahead. "We cut through the new tunnel in those mountains and we'll be in Atom City in ten minutes!"

There was a bustle of activity around them as other cadets roused themselves and collected their gear. Once again conversation became animated and excited as the train neared its destination. Flashing into the tunnel, the line of cars began to slow down, rocking gently.

"We'd better go right out to the spaceport," said Tom, pulling his gear out of the recessed rack under his seat. "Our ship blasts off for Venus in less than a half-hour."

"Boy, it'll be a pleasure to ride a spaceship without having to astrogate," said Roger. "I'll just sit back and take it easy. Hope there are some good-looking space dolls aboard."

Tom turned to Astro. "You know, Astro," he said seriously, "it's a good thing we're along to take care of this Romeo. If he were alone, he'd wind up in another kind of hunt."

"I'd like to see how Manning's tactics work on a female dasypus novemcinctur maximus," said Astro with a sly grin.

"A female what?" yelled Roger.

"A giant armadillo, Roger," Tom explained, laughing. "Very big and very mean when they don't like you. Don't forget, everything on Venus grows big because of the lighter gravity."

"Yeah," drawled Roger, looking at Astro. "Big and dumb!"

"What was that again?" bellowed the giant Venusian, reaching for the flip cadet. The next moment, Roger was struggling futilely, feet kicking wildly as Astro held him at arm's length six inches off the floor. The cadets in the car roared with laughter.

"Atom City!" a voice over the intercar communicator boomed and the boys looked out the window to see the towering buildings of Atom City slowly slide by. The train had scarcely reached a full stop when the three cadets piled out of the door, raced up the slidestairs, and jumped into a jet cab. Fifteen minutes later they marched up to one of the many ticket counters of the Atom City Interplanetary Spaceport.

"Reservations for Cadets Corbett, Manning, and Astro on the Venus Lark, please," announced Tom.

The girl behind the counter ran her finger down a passenger manifest, nodded, and then suddenly frowned. She turned back to Tom and said, "I'm sorry, Cadet, but your reservations have been pre-empted by a priority listing."

"Priority!" roared Roger. "But I made those reservations two weeks ago. If there was a change, why didn't you tell us before?"

"I'm sorry, sir," said the girl patiently, "but according to the manifest, the priority call just came in a few hours ago. Someone contacted Space Academy, but you had already left."

"Well, is there another ship for Venusport today?"

"Yes," she replied and picked up another manifest. Glancing at it quickly, she shook her head. "There are no open reservations," she said. "I'm afraid the next flight for Venusport with open reservations isn't for four days."

"Blast my jets!" growled Roger disgustedly. "Four days!" He sat down on his gear and scowled. Astro leaned against the desk and stared gloomily at the floor. At that moment a young man with a thin face and a strained intense look pushed Tom to one side with a curt "Excuse me!" and stepped up to the desk.

"You're holding three reservations on the Venus Lark," he spoke quickly. "Priority number four-seven-six, S.D."

Tom, Roger, and Astro looked at him closely. They saw him nervously pay for his tickets and then walk away quickly without another look at the ticket girl.

"Were those our seats, miss?" asked Tom. The girl nodded.

The three cadets stared after the young man who had bumped them off their ship.

"The symbol S.D. on the priority stands for Solar Delegate," said Roger. "Maybe he's a messenger."

The young man was joined by two other men also dressed in Venusian clothing, and after a few words, they all turned and stepped onto the slidewalk rolling out to the giant passenger ship preparing to blast off.

"This is the