Part 2

Only Clara Arnold showed worry. There was a slight shadow in her amber eyes, when she took Harwich's hand.

"I suppose this is only a preliminary test flight to Io and back," she said. "Not much dangerous exploration. But please be careful," she pleaded. "Please be careful, Evan."

The spaceman muttered a word of thanks. Evan. His first name. To have Clara Arnold use it like that might have given a new meaning to life. His heart was suddenly pounding very hard, before he remembered that diamond on her left hand. She was promised to George Bayley.

The girl and the printer retreated from the laboratory chamber, waving a farewell. The space ship was sealed. The great exit doors in the ceiling of the lab opened wide, and the air rushed out.

In another moment the RQ257 was shooting skyward. In the night, among the welter of stars, huge Jupiter and his many satellites shone down on the Ganymedean deserts. The nose of the ship swung unerringly toward Io.

* * * * *

The RQ257, wrapped in its protecting halo of blue fire from the Penetrator, struck the Forbidden Moon's tremendous, invisible envelope of energy, squarely. There was a snarling sound in the ship's interior. White sparks lanced through cold space beyond the windows of the cabin, as two opposed forces fought each other. But the RQ257 bored on steadily.

"We're going to make it, Paul!" Harwich shouted through the reeking, dinning cabin.

"Of course we are!" young Arnold yelled back at him. "How could we fail!"

The two men were on the brink of success.

Then there was an abrupt, strident, angry, snap from the vitals of the Penetrator apparatus. Everything seemed to happen at once. The protecting blue aura outside the ship waxed and waned perilously. And whenever it waned, there was a grinding, crumpling sound, as of steel plating being crushed like so much paper in a giant's grip. Heat, and the cindery pungence of scorched metal, filled the cabin.

Paul Arnold and Evan Harwich were frozen rigid with stunning, agonized paralysis, as strange energy snapped into their bodies. In the jolting, erratic motion of the wounded space ship, the two men were hurled from their feet like a pair of stiff wooden dolls.

Rolling and tumbling, his vision half blinded, Harwich saw the metal walls of the cabin buckle and redden with heat, as the craft floundered in that region of mysterious force and energy that heretofore had destroyed every ship that had attempted to reach Io.

There was another growl from the protecting apparatus. In a flash of electricity, the side of the bakelite case that housed the Gyon condenser exploded outward. At once the staggering Penetrator quit completely. Its last shred of protecting force was gone.

But that momentary hell had ended, too, with almost dazing suddenness. The grinding, snapping sounds had ceased. And there was only the heat and the stench of burnt metal, and the weightless sensation of free fall. That and the mocking stars.

Paul Arnold, panting, his face darkened and beaded with perspiration, clutched a bakelite handrail in one corner.

"We got through Io's energy barrage!" he shouted wildly. "We did that much, at least; and for a moment, when our Penetrator went wrong, I didn't think our luck would be even that good."

Evan Harwich leered back at the youth, from near the now useless apparatus that John Arnold had invented. "Yes, we got through," he grunted hoarsely. "The energy shell must be only a couple of thousand miles thick, with free space underneath, between it and Io itself. The Gyon condenser kept working raggedly just long enough to get us out of the danger zone, without being completely blown apart!"

Harwich didn't have to test the controls of the ship to know that they were useless, now. The rockets were silent too. The RQ257 was falling free toward the Forbidden Moon, still a couple of thousand miles beneath.

"But dammit, Evan!" young Arnold growled. "The Gyon condenser shouldn't have quit on us at all! Those things are tested for heavy loads of power!"

The patrol pilot was well aware of that. Clinging to the base of the Penetrator, he was close enough to see detail. The lights in the cabin had gone out, but the ugly effulgence of Io was streaming through the windows.

Projecting from the shattered bakelite box of the Gyon condenser, were two slender, bent wires that should have been joined together. It had been one wire once, but it had snapped in the middle.

The ends were faintly scorched and blued; but there was something else, too. They were bevelled off curiously, as if they had been notched.

"Cut with a file!" Harwich fairly snarled. "The wire was cut with a file. Then the insulation was rewrapped carefully so that all the evidence was hidden!"

The cause of the accident was plain. The wire had been able to carry the load of power easily enough during the tests; but under the additional load of fighting the Ionian hell-zone, it had burned through and snapped!

"Bayley!" Paul Arnold whispered in the ominous stillness that now pervaded the plummeting derelict of the RQ257. "He brought the condenser, you remember! Evan, I know you were careful to watch everything he did during the assembly and tests in the lab itself. He must have had the Gyon condenser at his apartment before he brought it to us. He must have doctored it there! He was planning even then to get rid of me! And when he found you around, he decided that he wouldn't weep if he got rid of you too!"

"But why?" Harwich growled in momentary confusion. "Why should Bayley want to get rid of you?"

* * * * *

It was almost a silly question, as Harwich realized at once; but now Paul was answering it.

"It's simple," said the youth. "Bayley financed me after Dad was killed--yes. He watched my experiments and tests and studied my apparatus. He has a pretty keen mind. With me out of the way, no one but himself will know just how the Penetrator works! He can fix up another ship and come to Io himself without any competition! Anything he learns or discovers on the Forbidden Moon will be his alone! Or so he thinks, anyway."

It was too clear now! Evan Harwich knew that he and the boy were tumbling helplessly into the maw of hell now. In a useless, derelict ship they were falling toward the Forbidden Moon! They were already within the gates of unholy mystery! Death seemed very close. Yet the cold anger that hissed in the patrol pilot's brain, made him determined to live, somehow, for revenge!

"We'll be smashed if we stay in the ship, Paul," he said fiercely. "So we've got to jump for it with our safety equipment."

Quickly and more smoothly than did the youth, for he was well-trained, Harwich got into his space armor. Next he donned two massive packs, one on his chest and one on his back.

The exit door of the cabin was jammed, but with his pistol the patrol pilot fired an explosive bullet into its hinges.

A second afterward, Arnold and Harwich crept through the rent, while escaping air puffed out around them. They leaped into the emptiness almost together. With the heat-warped wreck of the gallant old RQ257 falling beside them, they continued their plummeting descent. There were still almost a thousand miles to go, for the distance between Io itself, and the gigantic energy envelope that surrounded it, was perhaps three thousand miles.

Down and down, with only regulation spacemen's emergency equipment to rely on to avert being crushed on those greyish hills and deserts, rushing nearer and nearer. Even a thousand miles did not take many moments at that terrific speed.

The Forbidden Moon was like a sullen, silent nether world, with an atmosphere so rare that an unprotected human being would gasp and die in it in a few minutes! Even a man in a space suit could not hope to survive that desolation for long! Io seemed like a Pit now to Evan Harwich, an Abyss of Hell from which there was no escape! A place where no Earth being was meant to venture!

This moment was too grim to think of thrills. Helplessness removed that intriguing glamor utterly. And there was only savage determination left. That and smoldering hate of the man who had caused misfortune!

Presently, through the thin metal of his oxygen helmet, Harwich heard a soft, hissing, whistling sound. Gradually it grew stronger. The patrol pilot knew what it was, of course. He had entered the intensely thin upper atmosphere of Io, and the hissing was made by his own space armored body passing through those tenuous gases at fearful velocity.

The sound served as a signal for action. Again, though the situation was new to him, Harwich's training made his responses accurate. With a gauntletted hand, he groped for the metal ring on the pack that bulged from his chest. It was ancient history when he jerked that ring, but sometimes, in emergency landings like this, on worlds that had a blanket of air, however slight, it was still useful. In another second the patrol pilot was dangling beneath a gigantic mushroom of metal fabric. He felt the firm tug of the shrouds. Deceleration.

He wondered vaguely why the fragile parachute did not tear apart in the terrific speed of his fall. But it was the utter thinness of the air, of course, here in the upper layer. Its resistance was so very slight. So there was time for velocity to be checked gradually, as the air grew denser, and its retarding effect greater with lowered altitude.

Paul Arnold had opened his chute too. Its vast top, a hundred feet in diameter, gleamed dully in the faint sunshine.

In a great plume of dust far below, the derelict space ship crashed. Fire flew as the force of the impact generated heat. But the wreckage was out of sight, and there was only a pit smoldering on a bleak, dusty hillside. The RQ257 was buried deep.

* * * * *

Harwich and Paul Arnold landed several miles away from the grave of the ruined ship; for they had drifted with the thin, dry, frigid wind.

Their booted feet spanged painfully against the sand and broken rock, and they crumpled to their knees; for even in the feeble gravity of Io the impact had been heavy.

Harwich snapped on his helmet radio-phone. Young Arnold's voice was already audible in it, faint and thready and sarcastic.

"Well, here we are, Evan," he was saying. "The first Earthmen to set foot alive on the Enchanted World! I guess I got part of what I wanted anyway, didn't I? But with what equipment we've got to keep alive with, we might just as well be buried with the RQ257! Funny I'm not scared. I guess I don't realize...."

His bitterly humorous tone faded away in vague awe.

Still lying prone the two men, looked around them, at the hellish, utterly desolate scene. The hills brooded there under the blue-black sky and tenuous, heatless sunshine. A rock loomed up from a heap of sand. It was a weathered monolith with weird carvings on it, resembling closely those left by the extinct peoples of Ganymede, that other, now colonized moon of Jupiter. A curious pulpy shrub, ugly and weird, grew beside the monolith. A scanty breath of breeze stirred up a little ripple of dust.

That and the stillness. The stillness of a tomb. Harwich could hear the muted rustle of the pulses in his head. Everything here seemed to emphasize the plain facts. The Forbidden Moon was a trap to them now. A pit from which they could expect no rescue. An abyss that was worse than the worst dungeon--worse than being literally buried alive!

It was like the end of things. Was this the kind of slow, creeping, maddening death that George Bayley, the treacherous printer, had planned for them?

Again fury steadied Evan Harwich's determination. Grimly he struggled to steady his nerves.

"Listen, Paul," he said quietly into his phones. "We mustn't ever let ourselves think we're licked! That's sure poison! The stuff we've got in our emergency packs will enable us to keep living for a while anyhow. We know Bayley'll come to Io sometime, with a ship fitted out with a new Penetrator. We know he'll be looking for the secret of the force aura of the Forbidden Moon, and whatever else there is to find. Maybe we can get ahead of him yet, if we keep on the move. Which way do you suppose would be best to go?"

Harwich asked this question because Paul Arnold, in his more academic study of Io, should know more about its terrain than he.

"You know the Tower?" Paul Arnold questioned. "The queer pinnacle, or ruin, or building, near the equator, on what is known as the Western Hemisphere? You must have seen it often when you were on patrol."

Harwich nodded. He remembered very well. Only a hundred hours ago, still on duty as a patrol pilot, he'd seen that pointed mystery from the void, vague dusty movement around its base.

"It was my Dad's guess that whatever miracles are to be discovered on Io, they will probably be located around the Tower," Paul Arnold answered. "But I was careful to notice our position when we landed. We're far north of the Tower now--a good fifteen hundred miles. A nice, long walk--especially when the normal air of the Forbidden Moon is too thin to be breatheable."

"Stop that pessimist stuff, and let's get started!" Harwich snapped. "We'll have to live very primitively, of course, but who knows what will turn up?"

They discarded their parachutes and started out, plodding southward, carrying their heavy packs. As if to save their energy, they did not speak much.

The hills rolled past, under their plodding feet. More fragmentary ruins appeared, and were left behind. Their boots sank into soft dust, as they marched on and on. At first their muscles were fresh, but tiredness came at last. And the miles which lay ahead were all but undiminished.

The tiny sun sank into the west and the cold increased. Night was coming.

"We'd better camp," young Arnold suggested wearily.

So they opened their packs, and took out the carefully folded sections of airtight fabric that composed their tent. It was part of the usual equipment kept for emergency purposes by those in danger of being stranded on dead or almost dead worlds. The tent could be hermetically sealed. Harwich and Arnold set it up carefully and crept inside. Air was freed from their oxygen flask, and the queer shelter ballooned out like a bubble.

They could remove their space suits now, and breathe, here in the tent. They ate sparingly from their concentrated rations. Meanwhile a little pump and separator unit, driven by a tiny atomic motor, was busy compressing the thin Ionian air, separating out the excess of carbon-dioxide and nitrogen it contained, and forcing the oxygen into the depleted air flasks.

Once in the darkness Paul and Evan were awakened by a strange sound, eerie in that dead quiet, and very faint because the scant Ionian atmosphere could not conduct it well. But when they crept to the flexoglass window of the tent, they saw nothing unusual.

"I guess we're getting jumpy," Paul whispered nervously, his breath steaming in the cold, frosty air that filled the shelter.

"It looks that way," Evan Harwich returned reassuringly.

But after the boy was asleep again, he crept back to the frosted window to watch. He knew that there had to be something mighty on Io. The shell of force that surrounded the evil moon couldn't exist all alone. There had to be more. Something that lay back of it, went with it. Something that could easily be very dangerous.

Jupiter, so near to Io, was a gigantic threatening mass in the heavens. But its light was deceptive. There were so many dense shadows.

Did he see some of the stars near the horizon wink out suddenly, and then appear again, as though something big and nameless and sinister had momentarily blocked their light and then passed on? He could not be sure, and nothing further happened. To save his companion unnecessary concern, when nothing could be done about the threatening danger anyway, he decided to keep the incident to himself.

* * * * *

Long before the dawn they were once more on the march. How many hours was the Ionian day? Something over forty. It didn't matter much.

When the daylight finally came, they had slept again, this time in their space suits, without bothering to set up the tent. Rising to his feet, Paul Arnold pointed suddenly.

"Look! An ancient road!" he shouted.

It was true. The highway ran there between the hills. A stone ribbon, covered here and there with drifted sand, which showed that there was no traffic of any sort now. The ruins along it looked a little less battered than those which the two men had previously seen, and there were vast lumps of corroded metal, too. Machinery in a former age.

"The road goes our way," Harwich commented. "We'll follow it."

Hours later, Paul Arnold offered an opinion. "Part of the mystery of Io is clearing up, Evan," he said. "The ruins around here. They're almost identical in architecture to the ruins of Ganymede and the other Jovian satellites. The evidence looks plain. There must have been a single great civilization once, extending over all the moons of Jupiter."

Harwich, thinking of, and hating George Bayley for his diabolical treachery, was only half listening.

"Yes?" he questioned.

"Yes," the boy answered. "And look at those dry ditches, and the big, rusty pumps! The valley here must have been rich, irrigated farmland, once!"

They were going across a huge bridge, now, made of porcelain blocks. It was a magnificent structure, magnificently designed according to intricate principles of engineering.

"What I can't understand is why all this country became deserted," Paul offered. "You'd think that people who could build things like this would never die out! They could conquer any difficulty that might come up, it would almost seem. Even if their world got old and worn out. After all, even Earthmen can make almost dead worlds artificially habitable again with airdromes, and with imported atmosphere and water."

This was another mystery. But it touched Evan Harwich's thoughts only faintly. Nor did he care very much when later Paul pointed out to him rich deposits of ore--outcroppings along the road. He'd seen them himself, and the tunnel mouths, too, of ancient mine workings. There were many fortunes to be won here, in costly metals, just as on the other Jovian satellites. But how could this be important, now, with death dogging their tracks, and so many other things more important, to be concerned with?

Evan Harwich reserved his determination for what he knew was coming. The slow wearing down of stamina. Water he and Paul had a little of. And more could be reclaimed from the thin, dry atmosphere. It collected in the bottoms of oxygen bottles, when they were pumped full, condensed by compression. A few precious drops. You could drink it out after each bottle was emptied of air. Just about enough water to sustain life.

In the matter of food, you had to ration yourself so stringently that you caught yourself looking with longing eyes at the few, weird, bulbous shrubs and the scattered lichens, which were the only vegetation on this dying world. Only you knew that these arid growths would never be good to eat.

Those long Ionian days passed. One after another. Five, ten, fifteen. Harwich knew he was losing strength slowly. The inevitable was catching up with him. But those hard years in the Interplanetary Patrol Service, and the rigid physical discipline, had made him as tough as steel wire.

With the boy, Paul Arnold, it was not the same. He was very young, and not too robust. And he was slipping fast.

"What's the matter with me, Evan?" he would grumble. "All this desert isn't real, is it? We're not on the Forbidden Moon, are we? I'm dreaming."

"You're just tired out, that's all, fella," Harwich would answer in a tone that he would try to make reassuring. He would put an arm around the kid's shoulders, to support his faltering steps.

Big brother stuff.... Paul had plenty of pluck, all right, but there wasn't much else left in him. He was wearing out, mile by mile, staggering under his heavy pack.

* * * * *

Every resource was reaching its limit, now. Food supplies had dwindled away to nothing, at last. The little atomic motor that worked the air compressor and separator unit, was breaking down. It could hardly pump enough oxygen into the air flasks any more.

But there was nothing to do but keep on the march, anyway, in spite of handicaps. Evan Harwich felt as though he was going slowly mad. Brooding thoughts came into his mind constantly.

Clara Arnold. Where was she now? What had happened back there on Ganymede? What had George Bayley done? When would he come to Io, with the ship he would surely fit out with a new Penetrator?

What was Clara thinking? What if she knew her brother was alive on the Forbidden Moon, but slowly dying? What if Bayley told her that maybe Paul was still alive, adding that he himself was the only person that might be able to effect a rescue? What if he had finally used this means, this possibility, to make Clara marry him? She didn't love Bayley, the fat printer! She couldn't! And he wouldn't even have to promise to attempt a rescue--only suggest that he might try. Clara must be half crazy herself, thinking of her brother. After all she'd lost her father to the Forbidden Moon too.

The thought of demure Clara Arnold in the arms of that bulky, squint-eyed printer, who had shown his true colors at last, and proved his diabolical cleverness, fairly strangled Harwich. Maybe he had no right to harbor such an attitude. After all he hardly knew Clara. He only knew her haunting beauty and friendly amber eyes, with quiet wisdom and a little of the martyr in them--like her father, perhaps. But Harwich couldn't help thinking. It was only by exercising super-human self-control, that he kept himself from turning into a raving maniac.

Supporting Paul Arnold's feeble, struggling steps, Harwich watched the sky like a starved, wounded wolf. Sometimes, in sheer, wild determination, he longed to claw at that cold, forbidding firmament, and climb out of that hell-pit of a world into which he had fallen. He yearned with a savagery beyond words to claw his way up there into space, to wherever George Bayley might be, and feel the fat throat of the man who had tampered with the Gyon condenser aboard the RQ257, squeezed between his hooked fingers.

But the frigid sky and the bleak, dying hills, and the weary miles, mocked all his hate-born desires. His numbed, aching feet could only plod on and on in this grave-like desert. Ruins, rusted machinery, silence, and cold that crept even through the heavy insulation of his space armor.

Still, he could remember another thing. In the far distance to the south, was something wonderful and strange. Something that made the deadly and insidious energy barrier of the Forbidden Moon possible. Where the Tower loomed on the astronomical photographs of Io.

That night came at last when a streak of silver fire traced its way across the sky. It couldn't be anything but the flames ejected from the rockets of an approaching space ship.

Paul Arnold saw it too, turning his haggard face upward. "There he is, Evan," he croaked into his helmet phones. "Bayley's coming at last."

"I see," Harwich returned softly; his teeth gritted and his lips curling furiously, behind the transparent front of his space headgear.

They dropped down beside the wall of a ruin, to watch. The ship was coming straight in, toward Io. At its tremendous altitude, nothing but its rocket blasts could be seen at first. But then there was a sudden flare of bluish light. It had struck Io's force barrier, and that blue glow was the evidence of a Penetrator, functioning. The craft seemed to slow a little, as its pale, protecting shell of counter-energy fought back that invisible, guardian screen of the devil moon.