The yellow sands of the spaceport stretched, glaring and empty, in every direction. There was no sign of life from the little group of buildings a mile away.

In the control room of the tall, round-nosed starship, technicians labored and officers conferred while the red needles that showed rocket tube temperatures sank slowly toward zero on their dials.

"Maybe Earth's depopulated, Tom," suggested John Gray, the executive officer. He ran his fingers through close-cropped red hair and peered through the port with thoughtful gray eyes.

"Hardly, John," replied Commander Tom Wallace, frowning. "The scout rockets showed some good-sized cities, with smoke."

"I was off duty then and haven't had time to read the log," apologized John. "What gets me is that they should have a robot-controlled space relay station orbiting outside the atmosphere, and a deserted spaceport. It just doesn't jibe."

"That's why we have to be just as careful as though we were landing on an alien planet," said the commander. "We don't know what the conditions on Earth are now. How long has it been, John?"

"Two hundred and fifty-eight years," answered John. "Ten years, our time."

"Pick three for briefing, John. This is going to be a disappointing homecoming for the crew, but we'll have to send out an exploration party."

The landing ramp slid out from just above the rocket tubes, and the armored car clanked down to the sand. John steered it across the wide expanse of the spaceport toward the group of buildings. Above and behind him, a woman swept the terrain with binoculars from the car's observation turret. In the body of the car, another woman and a man stood by the guns.

The buildings were just as lifeless when they drew near, but there was an ominous atmosphere about them. They were windowless, of heavy concrete. Through slits in their domed roofs, the noses of a dozen cannon angled toward the ship.

"John, there's someone there," said the girl in the turret, tensely. "You can't see it through the windshield, but there are some smaller guns poking out near the ground and they're following us."

John stopped the car and switched on the loudspeaker.

"Hello, the spaceport!" His amplified voice boomed out across the sand and reverberated against the buildings. "Is anybody there? We come in peace."

There was no reply. The big guns still angled toward the starship, the little ones focussed on the car.

"They may be robot-controlled," suggested Phil Maxwell, the gunner on the side of the car toward the forts. "Any sign of an entrance, Ann?"

"Nothing but the gunports," replied the girl in the turret.

"Don't fool with them, John," said Commander Wallace, who was tuned in from the ship on the car's communications system. "If they're robot-controlled, they'll be booby-trapped. Move out of range and continue with your exploration."

Two days later, the car emerged from the desert into comparatively fertile country. The four explorers found a broken concrete highway and followed it between rolling, treeless grasslands. Near dusk, they saw smoke on the horizon—and ran into a roadblock.

A segment of the highway had been thrown up into a ten-foot wall, barring their progress. Over the edge of the wall, the muzzles of heat-guns pointed at them as they brought the car to a halt some distance away. John got the commander on the car radio.

"We could swing around it, but we don't know whether they have vehicles that could outrun us," he reported. "And my conception of our mission is to establish contact."

"That's right," agreed Tom. "But stay in the car until you get a friendly reaction. Then you're on your own—and I'm afraid you're expendable, John."

John switched on the loudspeaker and made overtures to the roadblock. After a moment, a lone figure stepped around the edge of the mound of earth and concrete and approached the car slowly. The man was dressed in the drab, baggy uniform of a professional soldier.

"If you come in peace, leave your vehicle and identify yourself," called the soldier. "You will not be harmed."

"Take over, Phil," ordered John. He slipped from the driver's seat and climbed through the turret. Jumping to the ground, he approached the soldier, his arms swinging freely at his sides.

"John Gray, executive officer of the starship Discovery, returned from a colonizing mission to Deneb III," said John, holding out his hand.

The soldier ignored the out-stretched hand, saluting formally instead.

"Arrive in peace," he said. "If you will leave your vehicle here, you will be escorted as deevs to Third Sarge Elfor, commander of the town of Pebbro."

John returned to the car and held a brief consultation with his companions. Although he was in command of the exploration party, planetary operations of the starship's personnel were conducted on a somewhat democratic basis. The commander listened in, but left them to their own judgment.

"Communications blackout for a while then, commander," said John. "I see no reason to let them know about the personal radios right now."

The quartet emerged from the car wearing small packs of emergency rations and equipment. Behind the roadblock, the sight that met their eyes was unexpected.

The robot-controlled space relay station, the heavily armed pillboxes at the spaceport and the heat-guns poked across the roadblock at them, all had made it logical to anticipate a powerfully equipped task force. Instead, they found a troop of 19th century cavalrymen, armed for the most part with 13th century weapons. There were no more than a dozen heat-guns in evidence, and their bearers also carried short swords and long-bows with quivers of arrows.

The four from the starship were given mounts and, with no outward indications of hostility, were escorted to the town whose smoke they had seen.

The town was another surprise. They had expected either a fortress or an outpost of brick and log buildings. It was neither. The buildings were tremendous cubes and domes of steel and concrete, sleek and modern, windowed with heavy glass bricks. Skeins of cables, coils and loops of aerials bespoke the power that must be at their command.

But the people walked.

Not a car or a truck was to be seen. Men and women in the gray military uniforms walked or trotted up and down the broad paved streets. Occasionally a horse-drawn wagon passed, hauling a load of vegetables or manure. It was as though a cavalry post of the old West carried on its slow-moving duties in a super-modern setting.

Third Sarge Elfor was a middle-aged man of military bearing, with a sandy handle-bar mustache. He sat behind a huge desk in one of the town's biggest buildings. There were elevators, open and deserted, in the lobby, but they had to climb ten flights of stairs to reach his gleaming office.

"The Topkick sends you greetings from Kansity, capital of the Earth," he said. "We have watched your ship since it approached the outer atmosphere. We have listened to your communications since you left your ship, and have been interested in the indications that you are of Earth but unfamiliar with it. We are interested also in your use of a vehicle that can travel for three days without refueling. But we do not find a record of any ship named Discovery, and we do not know what you mean by Deneb III."

"The Discovery left Earth 258 years ago," replied John. "We established a colony on Deneb III, the third planet of the star Deneb, before returning to Earth."

"You are the descendents of the ship's original crew, then?"

"No," said John. He explained as well as he could the extension of subjective time at near-light speeds.

"Mmm. And you have left a colony on a planet of another star." They could not tell from the Third Sarge's tone what he thought. After a moment's meditation, he said:

"We shall talk again tomorrow. Tonight you are our guests and will be accorded all courtesy as deevs. Are you husbands and wives, or shall we billet men and women separately?"

"However it suits your convenience," answered John. "You may billet us all together if you prefer."

Third Sarge Elfor took them at their word. They were conducted to a single room, evidently in the heart of officers' quarters. Here again they ran into the same anomaly that had impressed them since they landed.

There were gleaming electric fixtures, but orderlies brought them tallow candles as dusk fell. There was plumbing of the most advanced order, but when they turned the taps no water came. The orderlies brought buckets full of hot water for their baths in the bright-tiled tub.

"I don't understand this at all, Ann," said John. He was towelling himself vigorously, while she brushed the quartet's clothing clean of the dust of the road. Phil lolled in luxurious undress on one of the four beds, reading a book from the well-stocked bookcase. Fran, preparing for her bath, was binding up her hair before a full-length mirror. "Even the cold water doesn't run a drop."

"Plumbing gets out of order in the best of families, John," Ann reminded him with a smile.

He glanced affectionately at her. Blue-eyed, black-haired Ann had been John's companion in the six-months exploration of Deneb III, and their seven-year-old son now was learning to read in the starship's school. John and Ann clashed like flint and steel in the crowded confines of the starship and consequently maintained no association while aspace. But they were a happy team in the free, challenging atmosphere of a planet.

"Electricity, too, at the same time?" he asked. "And it's not just that. The whole place reeks of latent power and high science, but they use an absolute minimum of it."

"I've got a partial solution to the garrison state of affairs and the military set-up, anyhow," said Phil from the bed. "They've had a war since we've been gone."

"That's no surprise," commented Fran. Chubby, blonde Fran and dark, stocky Phil had been companions for a year aboard the Discovery. They had volunteered jointly for the exploration mission. "They should have had several of them in 250 years."

"This was an interplanetary war," retorted Phil mildly. "Or rather, it wasn't war, but occupation of the Earth by the enemy. The Jovians were smart enough not to attack Earth directly, but threw their strength at the crucial moment behind the weaker side in the war between Eurasia and the American Alliance. Then they moved in to take over the war-weakened victors."

"The classic role of the strong neutral," commented John drily. "What were the Jovians like?"

"Evidently everybody on Earth knew from first-hand experience when this book was written a century ago. There are no descriptions and no illustrations. There are some hints, though: methane-breathing, cold-loving. They had domed, refrigerated cities."

"What are you reading—a history book?" asked Ann curiously.

"Yes, it's the newest book of the whole lot, and the only one that isn't brittle and dog-eared. At that, it's the worst-made book of them all. It looks like it was printed on a hand-press and bound by hand."

"Pioneers, oh pioneers!" trilled Fran softly. "But what are they doing in the midst of all this technology?"

Supper in the officers' mess was a glittering affair in the military tradition. Their conversation developed some new revelations. Third Sarge Elfor was commander of the whole area that surrounded Pebbro for hundreds of miles, including the abandoned spaceport. The Topkick was ruler of the nation, and the nation was the top echelon in a co-operating hierarchy of countries of the world. For some reason, the simplified terms for enlisted men's grades had replaced higher ranks in Earth's military systems: such titles as "sarge" and "topkick." Inquiry developed that none of the officers was familiar with such designations as "captain" and "commander."

"But why is the spaceport deserted?" asked Phil. "Is space travel at such a low ebb on Earth now?"

"You are mistaken in thinking the port deserted," replied Elfor. "The big guns in the pillboxes are zeroed on your ship. If it tries to blast off, it will be destroyed."

There was no enmity in his tone, no threat. It was a simple statement of fact. He didn't elaborate, and the four from the starship discreetly asked no more about it.

After the meal, they retired with Elfor and several members of his staff to a quiet lounge. Like every other place they had seen in the building, it was lit with candelabra. They relaxed in comfortable, leather-covered chairs and the men enjoyed the long-forgotten luxury of good cigars. White-aproned servitors brought them wine in fragile, long-stemmed glasses.

"You asked about space travel from Earth," said Elfor. "Yes, you might call it at a low ebb. Yours is the first ship to blast down in fifty years, except the scout ships in the Jupiter sector.

"It is such an unusual occurrence that the Topkick is being informed daily of developments. When the men of your starship have been assured of our peaceful intentions, it will be hangared underground and the personnel quartered here until further orders from the Topkick. Meanwhile, you are the deevs of the hour and we shall drink to your return to Earth."

He stood and raised his glass. They all arose. The glasses clinked together.

"Conserve!" shouted the Third Sarge and gulped his wine.

It was a warm moment. For the first time, John felt the genuine glow, the thrill of homecoming, as he and Phil drained their glasses and performed the ancient rite of the spacemen when he sets foot on Earth once more. As in one motion, they hurled the empty glasses through the open door, to smash to pieces against the farther wall of the adjoining corridor. There was a second crashing tinkle on the heels of the first as the glasses of the women followed them closely.

It was only when he turned back to Elfor, his face alight, that John realized something was wrong. The Third Sarge stood with his mouth open in astonishment. There was something of horror on the faces of the other Earthmen. Dead silence hung in the room.

"Sleep in peace," said Elfor at last, in a strained voice. He turned on his heel and left the room. The staff members followed, coldly.

"Well, what do you make of that?" asked John, turning to the others with outspread hands. "Do you suppose those glasses were valuable heirlooms or something?"

"They looked like ordinary wine-glasses to me," said Fran. "I don't get it, but it looks like we slipped up somewhere."

The orderly who escorted them to their room cast an occasional side-long glance, full of awe, at them. Their heat-guns had been taken from their room.

"I don't know what we're in for, Tom," John said gravely into his pocket transmitter when he had tuned in to the ship. "This place is the biggest mess of contradictions I ever ran into. You'd think from the way they live that it's a decadent society living on the ruins of a former civilization.

"The perplexing thing is that they obviously have power and know how to use it, but don't."

"Your job is to find the motivation, John," replied the commander. "Remember, we couldn't understand the underground living habits of the Deneb IV natives until we lost half a search party in one of their semi-annual meteor showers. Do you have any recommendations for the ship?"

"I'd advise you blasting off and taking an orbit," answered John, "but every gun at the spaceport is trained on the ship. I wouldn't take any chances that they don't have atomic weapons. Despite these swords and spears, we've seen several regulation heat-guns around here."

"It might interest you to know that they're keeping us awake aboard with a battery of spotlights on us all night," said Tom drily.

"Spotlights." John swore softly. "And all we have to see by are candles!"

They didn't sleep well that night. They had the distinct impression that armed guards clanked by occasionally outside in the corridor.

There was no indication that they were prisoners the next day, however. Third Sarge Elfor and the other officers were cordial at breakfast and lunch, although they caught some quizzical glances directed at them from time to time. Their movements were not hampered. They were given the run of the town.

After noon their armored car was brought in, hauled by four teams of horses. Flanked by a troop of soldiers, it was pulled around a corner and vanished from their sight.

"If they're so curious about how it runs, why aren't they quizzing us instead of letting us go on a sight-seeing tour?" wondered Ann, staring after the disappearing vehicle.

"I've built up a theory on these Earthmen...." began Phil. But he was interrupted as an officer and a squad of soldiers approached them. The officer saluted smartly.

"Deev John Gray, Third Sarge Elfor sends greetings and desires that you confer with him. The others will be free to continue their inspection of the military city of Pebbro."

"Very well," agreed John. "Ann, you'd better come along with me to take notes on the conference. We'll see you two tonight, if not sooner."

He motioned to the officer to lead the way, and the group went up the street, leaving Phil and Fran standing in the shadow of a towering building.

"What's your theory, Phil?" asked Fran.

"Simple," he answered. "The Jovian war wiped out civilization. They've just climbed back up part of the way, but they still don't know how to operate the machinery and use the power they have available."

"I don't know about that," said Fran doubtfully. "They seem to know how to handle those cannon and searchlights at the spaceport all right."

"Automatic control, probably, or—" Phil paused. He was peering through a barred window at street level. "Say, Fran, look here! Unless I miss my guess, this is a central power station!"

Fran stooped to look.

"I think you're right," she said. "But it's deserted."

"Proof of my theory," he said triumphantly. "Now, if we can just find a door somewhere...."

John and Ann had been back from a very routine conference with Elfor for more than an hour, and were enjoying the informality of the officers' cocktail lounge in their building. They were aroused by a commotion in the street outside and, along with several off-duty officers in the lounge, ran to the window to see what was up.

Phil and Fran, seated in a military jeep, were surrounded by excited soldiers. Some sort of argument was in progress, and John and Ann heard the word "credentials" mentioned.

Just as several of the soldiers, with drawn swords, dragged the couple from the jeep, one of the officers from the lounge hurried to the scene. The soldiers stood aside and saluted. There was a heated discussion, with much gesticulating, then Phil and Fran were released and headed for the lounge.

The officer got into the jeep and shifted gears. All the soldiers whipped out their swords and stood rigid, presenting arms, as he drove it to the curb at the opposite side of the street. Then he turned off the engine and got out. A guard was posted around it, and a little later a team of horses arrived to pull it away.

"How did you people get into such a predicament?" asked John when the show was over and the four of them were enjoying drinks.

"Oh, I don't think it was as serious as it looked," said Phil lightly. "We ran across a whole garage full of jeeps. We drove that one all over town before this gang stopped us and wanted to see our written authority for driving it. Everybody else saluted us. That's the military mind for you."

"Didn't it occur to you that their objections might be something other than mere military regulations?" asked John in some asperity.

"Phil has a theory—" began Fran, but Phil silenced her with a shake of the head.

"My theory can wait until I have proof for it, and I expect that in short order," said Phil, winking at Fran. "We've made good use of our time while you and Ann were in conference."

Phil and Fran were eager to know what John and Ann had learned from their conference with Elfor.

"Not much," he confessed. "Elfor is pretty close-mouthed. He's more anxious to learn about us than to give us information about their set-up.

"We did find out, though, that they've located the records of the Discovery's departure in the archives of Kansity. There seems to be something irregular about it, but I couldn't get Elfor to go into detail."

The first hint John and Ann had of Phil's method of proving his theory was when he quietly stripped and went into the bathroom as they were preparing for supper that evening. Ann was about to remind him he had forgotten to get the orderly to bring his bath water, when they heard the sound of a shower roaring. All three crowded to the door, to find Phil luxuriating under a steaming downpour.

"What goes on here?" demanded John. "Phil, how did you know they'd started the water pumps?"

Phil smiled triumphantly.

"Try the lights," he suggested.

The others trooped back into the bedroom and Ann flicked the switches. White light blazed in the room, overpowering the feeble gleam of the candles.

"What is this, Fran?" asked John. "You were with Phil."

"We found proof of Phil's theory that these people just don't know how to operate their own machinery," replied Fran happily. "We found their main pumping station. It was in good shape, and it didn't take us long to get the engines started and the main switches thrown."

The electric lights suddenly faded and died, leaving them in candle-light again. At the same time, the sound of the shower gurgled to a stop in the bathroom. Phil appeared at the door with a towel, dripping.

"Don't tell me their machinery's given out so soon," he growled.

"Phil, this is no time to talk about discipline," snapped John angrily, "but you and Fran probably have pulled something a lot worse than the jeep this time. Neither of you is qualified in social psychology, but even so you should have been able to read the signs that they do know how to operate their machines. For some reason, they just don't operate them."

In less than five minutes, Third Sarge Elfor appeared at their door with a squad of armed men. All of these soldiers carried heat-guns.

"Two of you were observed in the vicinity of the power station today," said Elfor. "You are warned that you are suspected of having activated the power supply of the military city of Pebbro."

"We don't deny that," admitted John carefully. "We are ignorant of your customs, and hope no harm has been done."

"Your claim to ignorance will be determined at a formal hearing," retorted Elfor sternly. "We have given you the benefit of every doubt and treated you as honored deevs. I regret that this makes it necessary that all of you be placed under arrest. Your meal will be served to you in your quarters."

As soon as Elfor had gone, leaving armed guards outside their door, John tuned in the starship on his pocket transmitter.

"I would have advised against Phil's action, in view of our lack of understanding of the situation," he reported to Commander Wallace. "But I confess I wouldn't have anticipated that the result would be so extreme.

"I can't fathom their reactions, Tom. In a crazy sort of way, I suppose they fit in with all the other contradictions of their social set-up. Have you had any luck with the ship's calculator?"

"Not enough data," answered Tom. "Maybe this new stuff will help, and you might scrape for everything else you can transmit. I'd hate to try a rescue operation, because that might force us to head back for Deneb III. But if they don't decide to blast the ship in the next hour or so, there's a chance we can pull out of this trap at our end."

John did not ask for details, for he knew their conversation probably was monitored.

The four of them sat up half the night poring over the books in their room. They gleaned nothing except from the "history" Phil had been reading the night before. Unfortunately, it was not a general history, but the flowery story of a high military family. The sort of references they found were, "after the Jovian invaders had been driven from Earth" and "Second Sarge Vesix participated in the bombardment that destroyed the Jovian tyrants." No details.

What did emerge from their study was a picture of the rise of a military aristocracy on the ashes of an earlier civilization which had been ground to pieces under the heels of alien rulers.

There was good news from the starship at dawn.

"We're orbiting," said Commander Wallace with quiet pride. "Shortly after I talked with you last night, they called on us to surrender or be blasted. I asked time for a conference of officers and promised to fire a rocket from the nose if we decided to surrender.

"I fired the rocket all right, but it was an instantaneous smoke screen rocket. I still don't know whether their guns are manned or robot-controlled, but I gambled that their firing was keyed to the sight of the ship blasting off instead of to vibration. We were half a mile up before they could swing into action, and we didn't get a scratch."

A rescue mission with one of the scout rockets was too risky against the strong forces of the Earthmen. Tom mentioned that fast planes had followed them into the stratosphere. But one thing was done for the imprisoned four.

Soon after breakfast, they were taken under guard to a Spartan courtroom, presided over by Third Sarge Elfor.

"We have received a warning from your colleagues," Elfor said grimly. "They broadcast to us a short time ago that if harm came to you, this city and others will be destroyed before they leave the solar system. In case you knew of this and it has in any way raised your hopes, I wish to remind you that Earth's cities have been destroyed before. This threat will not affect our decision to mete strict justice to you.

"You are charged with being enemies of the people of Earth, and with having landed on Earth under false colors with the intent of sabotage and espionage. Your prosecutor will be Fifth Tech Jatoo, representing the nations of Earth. You will be permitted to speak in your own defense."

Jatoo was a slender, thin-faced man with the air of an experienced attorney.

"The governments of Earth make these charges against the joint defendants," he began matter-of-factly: "That they are members of a rebellious and traitorous group who are allied with the Jovians and maintain an illegal, secret base on some planet or moon of the solar system; that they came here under the guise of strangers, with the specific intent of espionage and sabotage of Earth's defense against the Jovian enemy; and that they actually began such operations.

"We shall present the following major evidence in support of these charges:

"First, that the defendants did travel from the Numex spaceport to the military town of Pebbro in a vehicle, the motive power of which is still unknown but which obviously must utilize fuel, in violation of the conservation laws;

"Second, that the defendants' colleagues did not approach the peoples of Earth in peace, but remained enfortressed in an armed space vessel;

"Third, that the defendants Phil Alcorn and Fran Golden did throw the switches activating the electrical system and powered water system of the military town of Pebbro, that the above-named two defendants did utilize a military power vehicle for pleasure purposes and that all the defendants did unnecessarily destroy glass drinking vessels, all in violation of the conservation laws;

"And, fourth, that the starship Discovery, listed in ancient records as having departed on a colonizing mission to the third planet of the star Deneb, was not scheduled to return to Earth for another seventy-five years and therefore could not be the ship in which the defendants arrived, as claimed."

Elfor inclined his head toward the quartet from the starship, who sat behind a long table on the side of the room opposite Jatoo.

"You may state what your defense will be," he said.

"Our defense to the first three items of evidence," answered John, who had been taking notes, "is that we have been absent from Earth for more than 250 Earth-years and that we were, and are, ignorant of your laws and customs. Thus, we are innocent of intent to violate them. Our defense to the fourth item of evidence is that certain improvements were made in the engines of the starship Discovery while colonization of Deneb III was in progress, making it possible for us to return to Earth ahead of schedule. Our defense to all three charges made against us is that they are false."

It was a monotonous trial, with a parade of witnesses brought to the stand by Jatoo, all of whom testified to seeing the defendants perform one or more acts of "unconservation."

"In the courts of Earth, a case can be decided only on the evidence presented," said Third Sarge Elfor when John had offered his brief defense for the quartet. "The defendants have presented no evidence, only argument. The fact that the defendants' clothing corresponds to that in use two and a half centuries ago cannot be considered competent, as it could be copied easily.

"For the safety of Earth, the defendants are found guilty and remanded for immediate execution. In view of the existence of doubt as to their treasonable intent and their previous status as deevs, they are accorded the honor of death by power weapons. Conserve!"

Shocked and silent, the four were led to a courtyard outside. As they walked, John switched on his pocket transmitter with a casual, almost unnoticeable gesture, and murmured a report to the ship.

"I'm sorry, John," said the commander, his voice tense with emotion. "There's no possibility of rescue, and I know it's small satisfaction to you that your deaths will be avenged."

The quartet's hands were bound behind them and they were lined up against a wall. The Third Sarge, attended by a good-sized retinue, stood at ease nearby, smoking a cigar, to direct the execution personally.

"'Power weapons' to them apparently mean regulation heat-guns," remarked Phil, almost jocularly. "That's what the fellow has."

A soldier was standing square in the center of the courtyard, a pistol dangling from his grip. At a signal from Elfor, he lifted it.

"Looks like I'm first," said John, bracing himself. "Be seeing you, somewhere."

He gritted his teeth for the wave of unbearable heat that was sure to come. Instead, there was a silent explosion in the midst of the courtyard and the soldier who had held the gun writhed on the ground, incinerated.

"John! The gun exploded!" cried Phil in amazement. "I've only seen that happen once before!—Remember that crewman who wouldn't take the trouble to keep his gun clean?"

John was thinking fast.

"I remember," he said in a low voice. His heart was still racing from the reaction of his near brush with death. "There's a pattern here. If I could only get a chance to talk over things sensibly with this Third Sarge...."

There was great excitement among the soldiery. Several of the men were crowded around the corpse of the marksman. Elfor stood nervously, his hand on his own holstered gun.

"They're concealing weapons," he barked to his aides. "Search them!"

A squad of guards swarmed over the four prisoners. There was an excited twitter when they discovered the pocket transmitters. They removed the little packets, snapping the aerial wires, and carried them to Elfor. He glanced at them, took one in his hand, and ordered:

"Execute them!"

Another guard with a heat-gun took his position in the center of the courtyard. He handled the weapon somewhat gingerly, but checked its mechanism and prepared to follow orders.

He waited for the command from Elfor. But the Third Sarge now was staring hard at the little transmitter in his hand. Instead of ordering the guard to fire, he strode across the courtyard and thrust the tiny radio before John's face.

"Is this true?" he demanded. He pointed at the well-known symbol stamped on the packet, the red diagram of an atom that warned against opening the lead-shielded mechanism without precaution.

"You mean, is it atomic-powered?" asked John. "Yes it is."

"It is a weapon?"

"No, it's a radio transmitter."

"But it operates?"

"Certainly it operates. Why in thunder do you think I'd be carrying a useless transmitter?"

"It has been many years since this sign was seen on a working mechanism on Earth," said Elfor soberly. "You are familiar, then, with atomic power?"

"I'm not an atomic technician," answered John carefully, "but there are several on the Discovery who can build anything from one of these little transmitters to the engines of a spaceship, with the proper equipment."

The Third Sarge stood in silent thought for several minutes. He was high in the councils of his country, or he would not have been commander of the zone that guarded Numex spaceport. He knew the reason for the basic slogan "Conserve!" and he knew, as 99 per cent of his subordinates did not, what circumstances would make that slogan meaningless.

"Guard!" he growled. "Unbind the deevs! John Gray, come with me in peace."

"You'd better give me back that transmitter, first," suggested John drily. "I'd hate to escape execution just to get H-bombed by my own ship."

It was the next afternoon that the four were escorted by a trim-uniformed guard of honor across the flat spaceport to the Discovery.

"The Jovians wanted to reduce Earth to colonial status, to be exploited for its natural resources," John explained to his companions as they walked. "All atomic installations were destroyed, all technicians and scientists exterminated systematically and all scientific books burned. They were very thorough about it.

"The successful revolt was accomplished with a concealed stock-pile of atomic weapons. Since that time, they've been garrisoned against the return of the Jovians. But atomic power was gone and so were the scientists who could bring it back and the books from which new scientists could learn.

"It's because they can't replace even so small a thing as an electric light bulb that destruction or unnecessary use of any sort of equipment is the rankest sort of treason. They've been saving all their technological capital for a last-ditch stand against the expected invasion.

"And it was their faulty, groping sort of maintenance that saved our lives, because even a heat-gun deteriorates in 150 years. That gun hadn't been fired since the Revolt!"

"Then we can be their salvation?" suggested Phil.

"Yes. The scientists who built the Deneb colony can rebuild the technology of our own Earth. It will take a long time ... there'll have to be schools and we'll all have to work hard ... but maybe some of us will be able to go back, in 30 or 40 years, say, when the Discovery can return to Deneb."

They were nearing the ship, and John saw the officers crowding the main port, watching them come.

"It's sort of inconsequential, I know," said Ann then. "But several times the Third Sarge referred to us as 'deevs.' Did he mention to you what a deev is?"

John smiled.

"It's an ancient military slang term, just like 'sarge' and 'topkick,'" he replied. "'Deev' is just plain old D.V. Distinguished Visitor. And I suppose we are, at that."