Chapter 17

. _Stronghold of the Lost Planet_

With a jolt that shoved the three men back in their seats, the rocket plane pushed out the cargo hatch, and slid into the dark of space on its own power. Behind them, the metallic surface of the _Magellan_ gleamed briefly, and then swung away on its orbit. Riding the red fire of their rockets, they headed on a long low dive for the mysterious surface below.

Pluto was a vast hemisphere, half lighted in the faint, dim glow of the tiny Sun, half in the total darkness of outer space. Here and there wound a silent, frozen river of glistening white. They passed over a gulf of some frigid sea of liquid gases, from which islands of subzero rock projected, and moved inland over a continent of lifeless grays and blacks. Haines gently drew the ship lower and lower, and at last the rocket plane bumped to the ground.

It rolled a few yards and stopped. The three men crowded to the door, tightened their face plates, and forced open the exit. There was a rush of air as the ship exhausted its atmosphere. Then, one by one, they stepped onto the bleak surface of the Sun's farthest planet.

"I feel peculiar," whispered Burl. "This planet reminds me of something."

"I have the feeling I've been here before," Russ said slowly.

Burl felt an odd chill. "Yes, that's it!"

Haines grumbled. "I know what you mean. I can make a guess. We've never really been the right weight since we left Earth. Even under acceleration there were differences one way or the other. But I feel now exactly as I did on Earth. That's what gives you the odd sensation of return."

The two younger men realized Haines was right. For the first time since they had left their home world, they were on a planet whose gravity was normal to them. It felt good and yet it felt--in these fearful surroundings--disconcerting.

Above them was the familiar black, unyielding sky of outer space. No breath of air moved. Yet somehow the scene resembled Earth. "It's like a black-and-white photo of a Terrestrial landscape," said Burl.

There was a field, some hills, a tiny frozen creek and the dark shapes of rounded mountains in the distance. All without color except for the cold, faint glow of the star that was the Sun.

A thin layer of cosmic dust lay over the surface, such as would be found on any airless world. Russ scooped beneath it and came up with a hard chip.

He squeezed it between his gauntleted fingers. It cracked and broke into powder. He whistled softly. "You know what this feels and looks like?" he said as they came close to the frozen creek on the little hillside. "It feels like dirt--common, Earthly dirt. Like soil. And you know what ... I can already tell you one of Pluto's secrets."

They stopped at the creek. It was a layer of frozen crystalline gases. Haines pushed the alpenstock he was carrying into it and scraped away the gas crystals. "I think I can guess," he said, "and I'll bet there is ice under this gas."

"Pluto was once a warm world with a thick atmosphere," said Russ. "Notice the rounded hills and the worn away peaks of the mountains. Those are old mountains--weather-beaten. This hill is round--weather-beaten. This creek, those rivers of frozen gas--they follow beds that could only be made by real rivers of warm water. The soil that lies beneath this dust--it could only happen on a world that knew night and day, warmth and light, and rain and wind. Pluto was once a living world, a place we'd have called homelike."

Burl shivered a bit. "Out here? So far from the Sun? How and when?"

Russ shrugged. "We'll find that out. But the evidence is unmistakable." They walked on.

There was a low, cracked wall on the other side of the hill, and beyond the wall stood the roofless ruins of a stone house, silent and gray in the airless scene.

They waited with surprise and uncertainty. Haines drew his compressed air pistol, but there was no movement. The scene remained dead and still--the windows of the house were dark.

They advanced on it and flashed a light inside. It was an empty shell. There was no glass within the unusually wide and low window openings, and no door.

"They went in and out the windows," commented Burl, ducking through one of the openings. "And they weren't built like us."

"No," said Russ, "there's no reason to suppose the inhabitants would have been built like human beings."

Inside there was nothing to see, and they left. Beyond, they found a straight depression in the ground filled with flat swirls of cosmic dust. "This looks like a road," said Haines.

They returned to the rocket plane in order to follow the dead roadway more easily. Passing between the low, dark cliffs of rocky mountains, they came to a plain marked by thousands of columns of rock, pieces of crumbling walls, and many straight depressions that must have been streets. It was the remains of a world that had died.

They found, as they traveled northward and made intermittent landings, that there had been many cities. Now all lay in ruins. There had been great roadways, now covered with the debris of outer space. There had been mighty forests, now miles of petrified black stumps. It was a gloomy sight.

In their landings, they had found inscriptions on walls and bas-reliefs carved on mountains. They knew from these what the Plutonians had looked like, and they had a suspicion of what had happened.

The Plutonians had been vaguely like men and vaguely like spiders. They had stood upright on four thin, wide-spread legs and had two short arms. Their bodies were wide and squat, and they seemed to have been mammalian and probably warm-blooded. They breathed air out of flat, thin nostrils and their heads joined their bodies without necks. Two oval eyes were set below a jutting bald brow. They had worn clothes, they had driven vehicles, they had flown planes.

Their vehicles had globe-shaped power plants. Their airplanes had globes where wings should have been. Their cities and their engines--which existed now only on wall pictures that were probably once advertisements--were built along globe-and-rod principles.

"There's no doubt," said Russ, "that the Sun-tapper culture and the Plutonian culture are the same. It's the descendants of the Plutonians that we are fighting."

"But how could they have survived?" Burl asked. "This world was never part of the solar system when it was warm."

"We'll soon know," said Russ. "Tomorrow we're going to see how far we can get into their polar redoubt. Somehow we've got to blow up that last station."

"And I think we three are going to do it," said Haines. "The _Magellan_ will never take the place from the sky. We'll have to do it from the ground."

Now they were reminded of Earth again. For the first time since they had departed from the United States, night fell. They had not been on any other planet long enough for such an experience. But the effect here on Pluto was mild.

Day was like a bright, moonlight night. Night then meant that the dim Sun had set and, in effect, it merely made the landscape slightly darker.

They compared notes late into the night in the rocket plane. By dawn, when again the dim glow shone, they had come to some very definite conclusions about the planet.

A number of the drawings on the walls seemed to have some religious significance. They focused on the phases of a moon. There were symbolic representations of this moon, passing through its phases; presumably Plutonian religious and social practices were related to it.

"But where is this moon?" Burl had asked.

"I think," Russ answered, "that what some astronomers had suspected about Pluto was right. It did not originate in the solar system, but was captured from outer space. Originally it revolved around another sun, some star which was light-years away. How it tore loose from that star we'll probably never know--the star might have simply become too dim, their planet might have been on a shaky orbit, an experiment of theirs might have jarred it loose, many things could have happened.

"Once beyond the gravitational grip of its parent sun, the planet wandered through the darkness of interstellar space until it came within the influence of our own Sun. How long this took would again be a guess. Possibly not more than a few thousand years, I'd say, since somehow a remnant of the population managed to survive. This suggests that they had some warning. Enough time passed for them to build the big structure we noticed at the north pole, probably to store food, build underground greenhouses and make sealed homes for a few families. Inside this giant building the last of the Plutonian people kept going.

"Then came the moment when their planet fell into an orbit around our Sun. I'd guess they emerged to find that the new Sun was too far away ever to heat up Pluto again, or to permit the rebuilding of an atmosphere. So they worked out a new scheme. This was to blow up the Sun into a nova--make it a giant and thereby bring its heat all the way out to Pluto--warming this world again, lighting it again, unfreezing its gases and waters. So they set up the Sun-tap stations."

"That also accounts," added Haines, "for their limited number of spaceships and their need for secret operations."

"Yes," said Burl, "but there are two things that don't fit in. What happened to their moon--surely it would have gone along with Pluto since it revolved around it? And second, why the thirty-year delay between the first Sun-tap stations and the completion and operation of them?"

There was no answer to these questions yet. The three began the morning's expedition.

As they neared the pole, they stayed close to the surface, for, any moment, they expected to see the dumbbell ships that patrolled the sky above it.

At last they set down the rocket plane on the edge of the polar plateau and got out. Not more than a mile away, the black ramparts of the building--a wall running miles across the horizon--rose hundreds of feet into the sky.

Above it, they caught a flicker from the forest of masts and the glint from a dumbbell ship. They moved silently forward, carrying the rocket launcher on their backs and a small load of shells and several hand bombs. These made heavy baggage, but the distance was not far, and the purpose great.

Burl felt like an ant about to creep into a human house. But he reflected that no ant ever had such dangerous intentions. An ant enters a house to steal a crumb of food. But if an ant had intelligence and evil intentions, it could cripple such a house.

Such was the situation for the three of them as they neared the precipitous walls. On arrival, they found that entry would be easier than they expected.

The Plutonian refuge had not been built to offset attack from the surface of the planet itself. It was no thick rampart of unbroken plastic as the walls of the other Sun-tap stations had been. Close up, it proved to have many doorless entryways, ramps running up to higher floors, even wiry monorail scaffolding, probably left behind by the builders.

They entered an opening in the base. Once inside, dim lights set in the ceiling lighted the path before them. They walked down this culvert like rats in a giant sewer until they came to a wall studded with several doors.

The doors were shut, but a tiny globe set on the surface of each one reacted to Burl's charged touch. Two opened upon dark airless passages. The third resisted a moment, and when it did open, there was a whoosh of air which raised a momentary cloud of dust on the stone floor of the culvert. This was obviously the entrance to the inhabited portion of the refuge.

The men closed the door behind them. They were in a small chamber. A door on the other side was opening automatically. "An air lock system," muttered Russ as they went through.

They were now inside the vast building itself. There was air, and, after testing it, they opened their helmets. The air was almost as thick as that of Earth, and they experienced no difficulty in breathing. It was stale and somewhat metallic in flavor, probably because it had been enclosed and used over and over for thousands of years.

They saw no living beings, which seemed strange. "Apparently these people really are at their last gasp," remarked Russ as they passed through an area that had obviously once been a large dormitory. They heard distant humming sounds somewhere in the floors above, but all that was visible on the lower level seemed to be maintenance machinery.

They walked through great storerooms which were piled high with sealed drums. They saw factories lying silent--curious lofts of odd machines powered by globes that were idle. They skirted an unlighted reservoir of water in a circular chamber far in the interior. And here and there in the gloom, they spotted huge ramps leading spirally upward.

Finally they turned their steps up a sloping ramp, mounting one floor and then another, and another. They were tired, but curiously exhilarated. They felt that they were about to strike at the heart of the foe, and that his days were numbered at last.

They emerged on a higher level, lighted more brightly than the others. Here they saw globes that glowed with the same intensity as those in the Sun-tap stations had. They moved carefully now, keeping out of sight, and several times they saw shadows in the distance or heard the thump of something moving.

They worked their way by instinct to what they guessed was the center of operations. They peered, at last, through a low, wide doorway into a large chamber. Here was a mass of mighty globes and rods, some revolving as they circled the metal masts that came through the room from the ceiling above.

"It must be the base of the Sun-tap receiver line," whispered Haines. "This should be a good enough place to set up our time bomb."

They stole over to a cluster of globes and unpacked the powerful little atomic bomb they had carried with them. They carefully put it together, inserted the explosive fuse, and set the timer. "I'm giving it four hours," said Haines. "Time for us to get out of here and radio the _Magellan_ to get into action. That should take care of this station."

They moved carefully out again, scarcely breathing for fear of some Plutonian entering and discovering them. They made their exit safely enough and started to retrace their steps.

Back down through corridors and strange chambers they moved, stopping every little while as something that sounded like footsteps passed over them. "Where," Burl whispered, suddenly troubled, "is the stolen heat and power of the Sun going? It isn't heating up Pluto. Surely they can't simply store it."

"Something we haven't solved," Russ replied hurriedly. "From what I remember of the masts, it looked as if they were relaying it somewhere else again."

"Can't imagine where," said Haines. "Not back into space, surely?"

They fell silent, concentrating all their energies on not losing the way. "Are you sure we came through here?" Burl asked nervously. "I don't remember this at all."

"I don't, either," said Russ. "It looks queer. Are you sure we're on the right path?" He turned to Haines.

The explorer shook his head. "We must have made a wrong turn. I think we've lost our direction."

They hastily conferred, and decided the best thing to do was to make their way to the lowest level and then outward--but suddenly they realized they could not tell which way was outward. There were no windows, and the wall markings and direction signs were unintelligible.

To make matters worse, they heard new noises, and, just as they dodged into a corner, five Plutonians shambled through.

These creatures were as the ancient wall sculptures had depicted them, though a bit smaller than their ancestors. They were pale, almost white in skin color, and their eyes were tiny sparks of red. They wore light harnesses around their bodies, and two of them were carrying tools. They spoke together in clacking bass voices. They shuffled loosely over the ground on their four thin legs. Burl thought of them as ugly caricatures of semi-humans.

When the creatures had passed, the three explorers darted out to where a ramp spiraled to the lower levels. They started down in single file, but it was too late.

Staring directly at them were two Plutonians who had come up from below. The men pushed past, but not before a barking voice had cracked out an order.

The Earthmen started to run down, followed by the scrabbling sounds of their pursuers. The barking calls increased in volume.

From somewhere a booming sound began, repeated over and over. As the men emerged on the floor below, they heard it repeated on every level. "The alarm's out for us," called Haines, making no effort to keep his voice down. "We've got to run for it!"

Laden with the remaining weapons and equipment, the three human beings hurried on, but it soon became clear that four legs were better than two, for the creatures were gaining on them.

They had forgotten they were lost. Now they sought only to get out of sight and hide. They dropped their equipment as they ran, down halls, through tunnels, skittering along sloping ramps, heading for what they hoped would prove to be an exit.

Behind them an increasing crowd of Plutonians had collected, and several times a spark of electronic power crackled and blazed against the wall over their heads. The pursuers were armed.

Burl's lungs began to ache painfully. Close on the heels of his companions he dashed into one room only to find a group of Plutonians coming at him from the other side. His ears were deafened by the barking noises and alarm boomings. He jumped to one side to avoid a Plutonian standing directly in his path, and ran into a narrow tunnel. There was an excited barking as the creatures followed him.

With a sinking heart, he realized that he was now alone. Haines and Russ must have been cut off. He gasped for breath. Running in a tight space suit, carrying his oxygen tanks, was hot and hard work. He did not dare drop the tanks, for his only chance was to escape outside.

He ran wildly on, hoping to reach an outer door. But he seemed now to be in a maze, for nothing was familiar to him. He could no longer remember how many times he had run into groups of Plutonians, nor could he guess how many followed on his heels.

Then he stumbled into a small, round chamber out of which led three tunnels. As he looked around quickly to select his next means of escape, barking Plutonians erupted from each opening. Burl backed up against the wall, knowing that this time he was trapped.

A blaze of sparks broke over his head as a blast banged across the room. The red-eyed, scrabbling figures charged, their chinless mouths opening to emit barking calls of bestial anger. One aimed a rodlike contrivance at him, and there was another flare of light.

The room dissolved around him in a glare of brilliant green. As he slipped helplessly to the floor, he lost consciousness.

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