Dick Penrun glanced up incredulously.

"Why, that's impossible; you would have to be two hundred years old!" he exclaimed.

Lozzo nervously ran a hand through his white mop of hair.

"But it is true, Sirro," he assured his companion. "We Martians sometimes live three centuries. You should know that I am only a hundred and seventy-five, and I do not lie when I say I was a cabin boy under Captain Halkon."

His voice sank to a whisper, and he glanced apprehensively about the buffet of the Western Star which was due now in three days at the Martian city of Nurm. Penrun's eyes followed his anxious glances curiously. The buffet was partly filled with passengers, smoking, gossiping women, and men at cards, or throwing dice in the Martian gambling game of diklo, which was the universal fad of the moment. No place could have been safer, Penrun reflected. Doubtless the old man's caution was a lifelong habit acquired in his youth, if he had actually served under Halkon.

Before long the old codger would be saying that he knew the hiding place of Halkon's treasure, about which there were probably more legends and yarns than anything else in the Universe. A century had elapsed since the death of the famous pirate who had preyed on the shipping of the Void with fearless, ruthless audacity and had piled up a fabulous treasure before that fatal day when the massed battle spheres of the Interplanetary Council trapped his ships out near Mercury and blew them to atoms there in the sun-beaten reaches of space. Some of the men had been captured; old Lozzo might have been one of them. Penrun knew the history of Halkon from childhood, and for a very good reason.

The ancient Martian stirred uneasily. His piercing blue eyes turned again to Penrun's face.

"Every word I have said is true, Sirro," he repeated hurriedly. "I boarded this ship at New York with the sole intention of discharging my sworn duty and giving a message to the grandson of Captain Orion Halkon, his first male descendant."

Penrun's eyes widened in startled amazement. He, himself, was the grandson of the notorious Halkon, a fact that not more than half a dozen people in the Universe knew—or so he had always believed. His mother, Halkon's only daughter, good and upright woman that she was, had hidden that family skeleton far back in the closet and solemnly warned Dick Penrun and his two sisters to keep it there. Yet this old man, who had singled him out of the crowd in the buffet not thirty minutes ago and drew him into conversation, knew the secret. Perhaps he really had been a cabin boy under Halkon!

"I have been serving out the hundred-year sentence for piracy the judges imposed on me, a century in your own Earth prison of Sing Sing," muttered Lozzo. "I have just been released. Quick! My inner gods tell me my vase of life is toppling. I swore to your grandfather that I would deliver the message. It is here. Guard well your own life, for this paper is a thing of evil!"

His hand rested nervously on the edge of the table. The ancient blue eyes swept the buffet with a lightning glance. Then he slid his hand forward across the polished wood. Penrun glimpsed a bit of yellow, folded paper beneath it. Then something tweaked his hair. A deafening explosion filled the buffet. Lozzo stiffened, his mouth gaped in a choked scream, and he sprawled across the table, dead.

As he fell, a fat white hand darted over the table toward the oblong of folded, yellow paper lying unprotected on its surface. Penrun clutched at it frantically. The fat fingers closed on the paper and were gone.

Penrun whirled about. The drapes of the doorway framed a heavy, pasty face with liquid black eyes. The slug gun was aiming again, this time at Penrun. He hurled himself sideways out of his chair as it roared a second time. The heavy slug buried itself in the corpse of the old Martian on the table. The face in the doorway vanished.

The next instant Penrun was through the door and racing down the long promenade deck under the glow of the electric lights, for the quartering sun was shining on the opposite side of the ship. Far down the deck ahead fled the slayer.

The killer paused long enough to drop an emergency bulkhead gate. Five minutes later when Penrun and the other passengers succeeded in raising it, he had disappeared. One of the emergency space-suits beside the air-lock was missing. Penrun sprang to a nearby port-hole.

Far back in space he saw the tiny figure shining in the sunlight, while the long flame of his Sextle rocket-pistol showed that he was checking his forward momentum as rapidly as possible. Unquestionably he would be picked up by some craft now trailing the liner, for the murder and theft of the paper must have been carefully planned. Penrun turned from the port-hole thoughtfully.

The liner was in an uproar. News of the murder had spread like wild-fire. Women were screaming hysterically and men shouting as they rushed about in terror, believing that the ship was in the hands of pirates. A squad of sailors passed on the double to take charge of the buffet. There would be an inquest shortly. Penrun started for his stateroom. He wanted to be alone a few minutes before the inquest took place.

His room was on the deck above. The sight of the empty passage relieved him, but he was surprised to discover that he had not locked the door when he left an hour ago. He stepped into the room.

Instantly his hands shot upward. Something was prodding him in the back.

"One move or a sound, and I shoot," warned a sharp whisper. "Stand as you are till I find what I want."

His billfold was opened and dropped with an exclamation of disappointment. The searcher hurried. Penrun calmly noted that the fingers seemed to fumble and were not at all deft at this sort of work. He glanced down, and smiled grimly. A woman! He jerked his body away from the prodding pistol, gripped the slender hand that was about to plunge into his coat pocket, and whirled round, catching the intruder in his arms.

Big, terrified dark eyes stared up at him out of a pale, heart-shaped face. Then with a sob the girl wrenched free, ran out of the door and was gone.

He did not follow, but instead carefully locked the door and placed a chair against it. Things had been moving too rapidly for him to feel sure he was safe even now. Opening his left hand, he gazed down at a bit of crumpled yellow paper he was holding there. That much he had saved of the message from his long dead grandfather when the murderer grabbed the folded paper from the buffet table and fled.

It proved to be the bottom third of a sheet of heavy paper, and on it was drawn a piece of a map, showing a large semi-circle, which might have been a lake, and leading off from it were what might be a number of crooked canals. At the end of one of these was an "X" and the word "Here."

Below the sketch were some words that had not been torn off. He read them with growing amazement. "... aves of Titan. I swear this to be the true and correct place of concealment of ... may he who comes to possess it do much good and penance, for it is drenched in blood and ... Captain Orion Halkon."

Penrun sat for a long time in thought. Titan, the sixth moon of Saturn! Nightmare of killing heat, iron cold, and monstrous spiders! How many men had died trying to explore it! And who knew it better than Penrun himself, the only one who had ever escaped from that hellish cavern of the Living Dead? Old Halkon had hidden his treasure well indeed.

Penrun had never found the Caves. Legend described them as the one safe place on the satellite where a man might live without danger of being attacked by the spiders because the Caves were too cold for them.

Penrun doubted if there was any place that would be safe from the monstrous insects.

At any rate old Halkon had hidden his treasure there, and that part of the map that Penrun had thought was a lake was apparently the main cavern, and the canals, side passages. Old Halkon believed that he had hidden his treasure well, but he could not foresee just how well. Two thirds of the map, showing the location of the entrance to the Caves, had been taken by the murderer of the Martian, Lozzo. The remaining third, which showed the location of the treasure inside the Caves, was in Penrun's possession.

The murderer could find the Caves, but not the treasure inside; and Penrun could find the treasure inside, but not the Caves.

Penrun folded up the crumpled bit of paper and placed it carefully in his shoe. Unless his guess was wrong, another attempt to get it would be made shortly. Undoubtedly the girl had by now reported her failure to the rest of the gang.

The inquest was brief. The white-sheeted body of the Martian lay on the table where he had been slain. The captain of the liner called Penrun as the chief witness. He told a straightforward story of a chance acquaintance with Lozzo who, he said, seemed to be afraid of something. He had declared, so Penrun testified, that he was being hounded for a map of some kind and he wanted Penrun to see it. Then the murder had been committed, the map was stolen, and the murderer had fled. That was all, Penrun concluded, he knew about the matter.

Other passengers corroborated his story and he was dismissed.

Throughout the inquest Penrun studied the crowd of passengers that jammed the buffet, hoping he might catch a glimpse of the slender, dark-eyed girl who had tried to rob him. She was nowhere to be seen. He thought of telling the captain about her, but decided not to. She might make another attempt to get the map, and thereby give him the opportunity of rounding up the whole gang, or at least of learning who they were. He told himself grimly that if he could lay hold of her again, she would not escape so easily.

If Penrun didn't realize before that he was a marked man, it was impressed on him more forcefully three hours later on the lower deck when two men attacked him in the darkened passage near the stern. There was no time for pistols. A series of hurried fist-blows. He slugged his way free and fled to the safety of his stateroom.

Once there he locked the door and sat down to consider his position. It was obvious now that he would be followed to the outposts of space, if necessary, in an attempt to get the map from him.

After half an hour's hard thinking he tossed away his fourth cigarette, loosened the pistol in his armpit holster, and slipped out of the room. He went to the captain.

"You think, then, that your life is in danger because you happened to be talking to that old Martian when he was murdered?" asked the captain, when Penrun had finished.

"No question about it," declared Penrun. "Two attempts have been made already."

"Hmm," said the captain, frowning. "A most remarkably strange business. I've never had anything like it aboard my ship in the twenty years I've been traveling the Void."

"I can pay for the space-sphere," urged Penrun. "My certificate of credit will take care of it with funds to spare. All you have to do is to let me cast off at once. If any questions are asked, you can say it was my wish."

"Hmm! Really, Mr. Penrun, this is a most unusual request. I'm not inclined—"

He stared at the communication board. The meteor warning dial was fluctuating violently, showing the presence of a rapidly approaching body—a meteor, or perhaps a flight of them. Gongs throughout the liner automatically began to sound a warning for the passengers to get into their space suits. The captain sat as though petrified.

Penrun sprang to the small visi-screen beside the board and snapped on the current. Swiftly he revolved the periscope aerial. There appeared on the screen the hull of a long, rakish, cigar-shaped craft which was overhauling the liner. The stranger was painted dead black and displayed no emblem.

"There's your meteor, Skipper," he remarked ironically. "And I am the attraction that is drawing it to your ship for another murder. Do I get the space-sphere?"

The captain sprang to his feet. "You get it, Penrun. You'll have to hurry. I want no more murders aboard my ship. Here, down this private stairs to the sphere air-lock. I'll make arrangements by phone. Once you are free of the liner I'll slow down so that the black ship will have to slow down, too. That will give you a chance to pull away and get a good start on them."

Five minutes later Penrun's newly acquired craft was sliding out of its air-lock in the belly of the monstrous liner. He pulled away and glanced back.

The liner was already slowing down. The black pursuing craft was hidden by its vast, curving bulk. Penrun crowded on speed as swiftly as he dared. By the time the strange craft had made contact with the Western Star his little sphere had dwindled to a mere point of light in the black depths of space and vanished.

Penrun leaned over his charts grimly, as he set a new course for the sphere to follow. He, too, could play at this game. He'd carry the battle to the enemy's gate. Out to Titan he'd go and match his familiarity with the little planet against the superior numbers of his enemies.

Ten days later, Earth time, he was circling Titan, while he searched the grim, forbidden terrain beneath. After days of studying and speculation he had decided that the Caves must be situated in the Inferno Range, a place so particularly vicious that no man, so far as was known, had ever explored it. During the day the heat would boil eggs, and at night the sub-zero cold cracked great scales off the granite boulders. And here, too, lay the Trap-Door City of the monster spiders!

The grim, fantastic range soon appeared over the horizon, stabbing its saw-tooth peaks far into the sky. Dawn was still lighting the world, and a great snow-storm, a howling, furious blizzard, concealed the lower slopes of the mountains. Penrun knew that presently the driving snow-flakes would change to rain-drops, and the shrieking, moaning voice of the gale would give way to the crashing, rolling thunder of the tempest. As the day advanced the storm would die abruptly and the clouds vanish under the deadly heat.

Then the Trap-Door City, which covered the slopes above the plateau at the three-thousand-foot level like a checker-board of shimmering, silken circles, would spring to febrile life as the spider monsters went streaking and leaping across the barren, distorted granite on the day's business, the hunt for food in the lowlands, and the opening of the trap-doors to gather in the heat of the day in the silken tunnel homes set in the gorges and among the boulders. At sunset the doors would all be closed, for then the rain and the electrical storm would return, and at night the blizzard. The storm-and-heat cycle was the deadly weather routine of the Infernos.

Penrun steered for a tall, cloven peak that towered high above the Trap-Door City. In its thin air and continuous cold he would be comparatively safe from marauding spider scouts, and from the peak he could watch not only the city of the monsters but the better part of the Inferno Range as well.

He was convinced that before long the mysterious black craft would put in an appearance somewhere near this spot. Penrun knew it all too well. There by the cataract of the White River, half a mile across the plateau from the insect city, he had once been captured.

Next morning when he looked down on the plateau just below the Trap-Door City he laughed triumphantly. There sat the long black-hulled space craft he had seen overhauling the liner.

But a moment later he shook his head dubiously. Too brazen, that landing. It was almost in the insect city. Of course, the ship was large and heavily armed with ray-guns which poked out their sharp snouts here and there about the hull. None the less, an experienced explorer of Titan would never have flung such defiance at the spiders.

The city was feverishly alive with the monsters now. They gathered in groups to stare down at the strange craft, then raced away again, darting in and out of their trap-door homes and streaking here and there across the twisted, tortured granite of the mountainside. The Queen's palace, a vast, raised cocoon of shimmering, silken web, was a veritable bee-hive. Something was brewing!

Abruptly the trap-door homes vomited forth monstrous insects by the thousands which spread with prodigious speed along the mountainside. At an unseen signal they poured down upon the plateau and charged the space-ship.

The black craft's heavy ray-guns broke into life. Attacking monsters curled up and died as the rays bit into their onrushing ranks. The first wave melted, but an instant later the following waves buried the ship.

Insects in the rear darted here and there, dragging away dead and dying spiders. Here was food aplenty! The denizens of the Trap-Door City would live well on their dead for a few days.

Abruptly the attack ceased. The crackling ray-guns were still taking toll as the monsters scurried back to the safety of their city, leaving their dead piled high about the hull of the ship.

Penrun wondered if the monsters would abandon the heaps of their dead. He rather expected that frenzied efforts would be made to retrieve them for food. The problem was solved by those aboard the space-ship, for presently it rose a score of feet in the air and moved a few hundred yards nearer the waterfall that marked the headwaters of the White River.

At once a frantic wave of spiders swept down across the plateau scouring it clean of the dead monsters.

After that the Trap-Door City seemed deserted. Not a spider could be seen near the shining, circular doors. Only here and there crouched a huge, bristly warrior safe behind a jutting rock with his glittering eight eyes fixed on the motionless black ship below.

Again the weary waiting. Penrun could only hope that it would not be long before those aboard the black ship gave him some hint of where the entrance to the Caves might be. Time and again he trained his glasses on the ship only to drop them resignedly. But when noon had passed and the heat of the day was scorching the rock he did not drop his glasses when he looked through them once again. Instead he stood erect in horror and dismay.

A girl had dashed out of the air-lock of the ship. She seemed to be familiar. Then he recognized her as the girl who had tried to rob him aboard the Western Star. Her face was drawn with agony in the stifling, overpowering heat. She had advanced but a few yards, but she was already staggering uncertainly.

What in Heaven's name possessed her to try to venture out in that killing heat? She wasn't even dressed in a space-suit, which would have protected her against heat as well as cold. There was the danger of the monster spiders! Rescue would have to be quick!

Even as the thought flashed through his mind he knew she was past saving. Down from the nearest pinnacle of rock streaked a gigantic spider. The girl saw it, screamed, clutched her throat and fell. Ray-guns of the ship crackled frenziedly. In vain! The insect swept the helpless girl up in its powerful mandibles, sprang clear over the ship and was streaking back up among the rocks in a black blur of speed before the men inside the ship could train the guns on that side, even if they had dared to.

Penrun watched with fascinated dread. To the cavern of the Living Dead! The monster carrying the limp girlish form was now running up through the city toward it, guarded by two other huge insects that had appeared from nowhere. Through the entrance of the cavern they darted and disappeared.

Surely those aboard the ship would make an effort to rescue her, thought Penrun, tense with horror. At least they would retaliate by raying the city with their heavy artillery. But no! The black ship only continued to rest there wavering in the heat. Penrun swore vividly. The cowards! Still, perhaps they were afraid to unlimber their heavy artillery for fear of killing the girl. Or perhaps, which was more likely, they thought she was already dead and devoured. Few persons knew about the Living Death.

Ah, well, he'd forget about her. She was an enemy, she was one of the group that was trying to rob and perhaps kill him. Perhaps her companions knew that she wouldn't be killed for two or three days, and would make an effort to rescue her. And perhaps they wouldn't.

But before an hour had passed Penrun knew that he was going to master his horror of that cavern and save her himself, or die in the attempt. He, and he alone, had been in the cavern of the Living Dead and knew what to expect—the fate that might be his as well as the girl's.

He wondered if that Englishman, that old man with the great beard who said he had known Shakespeare and Bacon personally, was still lying in his silken hammock at the far end of the cave. Know Shakespeare personally? Impossible! Yet was it more impossible than the cavern itself? The man's English was quaint and nearly unintelligible. His description of that comical old space-ship of brass and wood was plausible. Perhaps he had known the Bard of Avon.

Night had descended when Penrun finally emerged from his little ship. The air was bitterly cold, and overhead the stars burned brilliantly. He paused to marvel a little that the Big Dipper, Cassiopeia, and the other constellations appeared just the same out here hundreds of millions of miles from Earth as they did at home. It made one feel infinitely small to realize the pinpoint size of the Solar Universe. He shivered for the temperature was nearly forty below zero, and snapped on the current of his Ecklin electro-heater which was connected with his clothing and would keep him warm even in that cold.

Another suit of slip-on clothes with an Ecklin heater, and his lounging moccasins were in a pack on his back. If he succeeded in releasing the girl, she would need them. The spider monsters didn't leave their Living Dead victims any clothing usually; and little good would it have done the Living Dead if they had.

Swiftly he descended the peak, leaping easily from rock to rock, thanks to the small gravity of the planet, and presently entered the clouds above the insect city. Abruptly the storm broke in all its fury with the shrieking of the gale and driving snow. In the blackness the pencil of light from his tiny flash showed only a few yards through the swirling, driving flakes that bit and numbed his bare face. With pistol ready he forged slowly ahead toward the cavern of the Living Dead.

He bumped into the snow-covered rock before he realized he was close to the place. With every nerve alert and the shrieking, freezing gale forgotten he slipped the flashlight back into its holder and drew another pistol. The door, he recalled, opened inward. It was not fastened, but just inside the entrance crouched a gigantic insect on guard.

Penrun was tense and ready. He kicked the door so viciously that its elastic, silken frame sagged inward under the impact of his foot. Against the glow of the green light inside the cavern he saw a nightmarish monster rising to its feet. Both pistols stabbed viciously as the monster thrust forward a thick, bristly leg to shut the door again.

Aray bit off the leg at the second joint. The other ray ripped open the soft, tumid abdomen. Penrun had barely time to throw himself aside as the convulsed, dying monster hurled itself tigerishly forward through the doorway out into the driving storm in a final frenzied effort to seize and rend his frail human enemy.

Penrun slipped into the cavern. The deathly cold outside would finish the horrible insect. As he kicked the big door shut he was crouched and tense, for the ancient gray attendant monster whose poisoned bite had paralyzed thousands for this living hell was moving forward curiously.

Both pistols flamed to life. The fearsome head of the monster with its poisoned mandible shriveled to nothing under the searing rays. Penrun sprang backward and jerked open the door. Then he closed it again. The old spider was moving feebly. Instead of the galvanic death of the guard, the huge gray insect's legs buckled under it and it slumped down to the floor of the cave where it quivered a few seconds, then relaxed in death.

As Penrun stepped forward around the carcass the cave filled with hysterical screams and hoarse insane shouting of joy and terror. He looked up at the high vaulted roof where the strange diamond-shaped crystal diffused its green light along the shimmering silken web, then turned his gaze downward to the rock floor beneath his feet. At last he gritted his teeth and forced himself to look at the walls.

Again he saw tier upon tier of hammocks, each holding a naked human being, helpless and paralyzed from the poisoned bite of the attendant monster spider. Some could weep, some could smile, some could talk, yet none could move either hand or foot. A few were mercifully unconscious, but the rest were not. Many were insane. Yet they all lay alike year after year, century after century, if need be, kept alive by the rays of the strange green light in the roof. This was the cavern of the Living Dead!

Penrun knew the tragic future of these unfortunates. A few, perhaps, would go as food for the Queen in times of famine. The remainder would become living incubators for the larvae of the Queen which would be planted in their living bodies by the monster attendant to eat away the vitals until death mercifully ended the victim's life, and the growing spider emerged to feed on a new victim, or to go its way.

A thousand helpless human beings swung in their silken hammocks awaiting their fate. Penrun had learned about them during those two horrible days he had been held prisoner here before he had succeeded in raying the novice attendant and the monster guard with the pistol from his armpit holster that the spiders had overlooked when they captured him. He recalled again how he had dashed frantically from hammock to hammock trying to rouse some of the Living Dead to escape with him. Not one of them could respond.

Reports to the Interplanetary Council? He had made them, written and oral, and had only been laughed at for a half-crazy explorer. The Council would not even investigate.

Now Penrun did not tarry. He strode swiftly back to the far end of the cavern.

"The girl who was just brought in, is she safe?" he asked hoarsely.

None seemed to know, but presently he knew she was still unhurt, for he found her bound hand and foot to the rock wall with heavy silken webs. Nearly all her clothing had been torn off her. She looked up hopelessly. A great fear appeared in her eyes.

"You!" she gasped. "Are you responsible for this?"

"I have come for you," he replied in a matter-of-fact tone, swiftly removing the pack from his back.

She cowered against the wall.

"You—you inhuman beast!" Her face was white with horror.

He cut the silken bonds.

"Don't be a fool!" he said roughly. "I have no power over these monsters. Hurry into those clothes! Do you want to be bitten in the small of the back and lie paralyzed for years in a hammock like these other unfortunates, then suffer untold agony for months while spiders' larvae eat out your vitals? Hurry, I say! We must get out of here at once!"

He turned away. He wanted to see that old Englishman who said he had known Shakespeare. His wish was in vain. The old man's sightless eyes stared up at the silken roof. The long, heavy beard that lay across the breast stirred. The beady, glittering eyes of an infant spider peeped out. Penrun uttered a curse of loathing. His pistol stabbed death into the foul insect.

He felt a touch on his arm. The girl was waiting.

"I am ready," she said quietly. "Oh, let us hurry!"

Dawn was lighting the world outside, and the driving blizzard was already changing to rain. Penrun seized the girl's hand and ran madly up the mountainside toward the peak. The spiders usually did not venture out in the rain, but in the face of danger from the ship they would be abroad as early as possible this morning.

Penrun suddenly spurted madly. Half a dozen gigantic spiders were moving cautiously along the lower edge of the city, their bodies looming up grotesquely in the misty rain. The girl stumbled, struck her head against a boulder, and lay still. Penrun caught her up in his arms and sprinted madly up the steep slope.

Arock loosened by his flying feet rattled and pounded down the hillside. Instantly the monsters whirled round, sighted him and started in pursuit. With a mighty leap he cleared a ten-foot ledge, carrying his unconscious burden, and plunged into the sheltering mist of the clouds. Up, up! Thank God for the weak gravity!

A swishing rattle of claws on rock shot by them in the fog, turned and swept back. Penrun sprang straight upward, rising nearly a dozen feet in the air as the monsters streaked past underneath.

Only a little farther! Savagely he forced his failing strength to carry them up the slope. The air was chilling fast and the mist thinning. He broke into clear air as the fog behind them filled with the rattle of racing claws on the barren granite and the grating roar of the baffled monsters, seeking frantically for their intended victims.

He staggered on another hundred yards before he collapsed with lungs laboring desperately in the rarefied air.

Below them a bristly monster charged out of the fog, sighted them lying up among the rocks, and leaped after them. Penrun jerked up a pistol with trembling fingers and loosed its deadly ray. The huge spider stumbled and ploughed head-on among the rocks with a flurry of legs. It rose loggily, for its fierce energy was dwindling rapidly in the biting cold. Again the pistol crackled. The gigantic insect toppled over and rolled down the mountainside into the fog and vanished.

"Are we safe now?"

Penrun turned. The girl was now sitting up somewhat unsteadily, with an ugly bruise on her forehead.

"I think so," he replied. "Up there in my space-sphere we shall be quite safe."

Together they plodded silently up the sharp incline of the peak, her hand in his. And as they went he marveled that her eyes could be so beautiful now that the fear and horror had vanished from their depths.

The storm clouds below had broken up and dissolved under the increasing heat, revealing the Trap-Door City, seemingly deserted, and the motionless black ship still resting on the plateau. Penrun turned to the girl beside him in the control nest of the space-sphere.

"What are your friends waiting for all this time?" he asked abruptly.

"They're not my friends," she retorted. "And you might have guessed that they are waiting for you to arrive with the other third of the map. They are planning to surprise you and rob you of it. The entrance to the Caves is under the edge of the Cataract over there, and by waiting here they are sure to be on hand when you arrive. Only"—her brows puckered in a little frown—"I don't understand why they remain out there on the open rock after Helgers has picked a hiding-place for the ship."

"Helgers?"

"He is the leader of the gang, and he is the man who killed that poor old Martian aboard the Western Star for the map. Helgers learned about the treasure and the existence of the map through a convict who was with Lozzo in the prison. Helgers pretends to be an importer in Chicago—he actually owns a nice little business there—but in reality he is one of the biggest smugglers in the Universe."

"How do you come to be with him?"

"I was coming to that," she replied. "My parents live on Ganymede."

Penrun nodded. He was familiar with the fourth satellite of Jupiter and its fertile provinces.

"My father is an American, but my grandfather on my mother's side was a Medan nobleman. He was ruined by that notorious pirate, Captain Halkon, who descended with his ships on our city and carried off everything of value, including the vast amount of scrip credits owned by the state which were entrusted to my grandfather. You know the Ganymedan debtor's law?"

He did indeed! It was one of the most infamous laws of the Universe: ruling that the debts of the father descended to the children and their children's children until paid.

"My family is now poor," she went on. "For a century or more we have striven to pay off the debt caused by the loss of those state funds. That's the way matters stood when I received a letter from my brother Tom in Chicago, who was employed in the office of Helgers' legitimate importing business, little aware of the smuggling. Tom had somehow got wind of the near discovery of Halkon's treasure, and I saw a chance to get a part of it by joining Helgers' party. He might not want us, but he would be practically forced to take us to keep our mouths shut. I felt that we were honestly entitled to a part of that treasure which had been stolen from our family, and with it we could pay off that old debt that had ridden our family like an Old Man of the Sea for more than a century.

"Getting into the expedition proved much simpler than I had expected. When Tom told Helgers about me he was very eager to help us—he is one of those men who is always anxious to help a girl if he thinks she is good-looking enough. So you see when I held you up in your stateroom I was merely performing my part of the scheme, although I didn't know then that Helgers had already slain the old Martian and leaped out into space.

"After that the Osprey—the ship down there on the plateau—overhauled the Western Star and took us off, and shortly afterward I learned most unpleasantly that Helgers had no intention of giving Tom and me our share unless I gave myself to him in exchange. I told Tom, and trouble started. It came to a head yesterday and there was a fight and—and Helgers killed Tom."

She began to weep quietly. Penrun stared grimly down at the black, motionless ship. Presently the girl resumed her story.

"I managed to get the air-lock open and escaped from the ship. Then that horrid spider caught me. You know the rest."

Her voice trailed off. Penrun remained silent for a while.

"You haven't even told me your name," he reminded her gently.

"Irma Boardle," she replied with a wan smile.

"I am Dick Penrun, in case you don't already know me. Captain Halkon was my grandfather. We always tried to keep the knowledge of it a family secret, since we were ashamed of it. If I—we get our hands on that treasure, I can promise you that the debt hanging over your family shall be paid first, Miss Boardle."

"Not Miss Boardle. Call me Irma," she said, the wan smile growing suddenly warm.

Penrun looked at her thoughtfully.

"But we aren't near the treasure yet," he said. "Between the spider monsters and the human monsters in the ship, our chances are rather slim. We'll just have to wait until we get a break."

As the day wore on there was a note of menace in the silence that hung over the Trap-Door City. It was nothing tangible, unless it was the appearance of two long silvery rods mounted on the top of the huge cocoon-palace of the Queen aiming down at Helgers' ship. Penrun could have sworn they were not there yesterday. The sight of them made him uneasy.

Helgers must have interpreted the silence differently, for presently a man emerged from the ship, protected against the heat by a clumsy space-suit. He hesitated, then walked slowly away from the ship, and paused again, waiting for the spiders to attack. Not a movement was made in the city. Presently he moved on again toward the cataract which had dwindled in the heat of the day to a mere trickle of hot water down to the pool in the gorge more than half a mile below.

After a time the man reached the cataract. He descended the short path that led down under the lip of rock to another ledge a few feet below it. The entrance to the Caves opened out onto this lower ledge. Little wonder, thought Penrun, that no one knew where the Caves were.

Some time later two other men from the ship followed him.

"Fools!" muttered Penrun, following them through his glasses. "They think the spiders are afraid of their ray artillery. I'll bet the monsters are either waiting until all the men wander out of the ship, or else they're getting ready to spring some hellish surprise."

Other men came out of the ship, carrying rock drills, a roll of cable and a powerful little windlass. Instead of going to the Caves, they went round the ship to the other side under the doubtful protection of the ray-guns, and sank two shafts into the granite. Into these they drove steel posts and anchored the windlass. One end of the cable was attached to the windlass and the other to the nose of the ship. Then they slowly dragged the big craft across the plateau on rollers from the ship's store room.

"That's strange!" exclaimed Penrun. "The ship can't rise! I wonder what's wrong, and why they are pulling it away from instead of toward the Caves."

"I don't know what's the matter with the ship, but I believe I know why they are moving it," volunteered Irma. "They're taking it to that hiding-place I told you Helgers picked out—there behind that upthrust of rock. You see, they think you know where the Caves are because you have explored Titan, and they think you will come directly here, so they want the ship hidden to make sure you land."

Half a hundred men in their space-suits toiled like ants about the big cylindrical craft until they at last jockeyed it into position behind the natural screen of rock. Even before it was in place other men were swarming over the ship with paint machines, coloring it a granite gray. When they had finished the ship was nearly invisible from the sky.

Penrun paid little attention to their preparations. His attention was centered on those two shining rods atop the Queen's silken palace. They now aimed at the ship in its new position. A strange idea flashed through his mind. Those rods had in some mysterious way put the elevating machinery of the Osprey out of commission!

Suppose the spiders turned them next on his own space-sphere up here on the peak? The thought sent a shudder through him. Visions of the final flight across the nightmarish, distorted granite, the running down and capture of himself and Irma, the paralyzing bite of the monsters in the cavern of the Living Dead flashed across his mind. Cold sweat stood out on his forehead. Instinctively his hand leaped to the propulsion control and hovered there.

Yet why hadn't the spiders attacked the ship, now that they had it helpless? It was not their usual tactics to give their victims a chance to free themselves. Why, why? There could be only one answer. They were waiting for something! Penrun's eyes glinted suddenly.

"Irma," he said rapidly, "we are in serious danger. The spiders have obviously put the elevating machinery of the Osprey out of commission. Helgers and his men are doomed to the Living Death as surely as though they were already lying in the silken hammocks. If the monsters choose, they could do the same thing to our sphere and doom us to the same fate. I believe they are waiting for something. While they wait we have a chance to get the treasure and escape. Shall we risk it, or shall we go while we know we are safe?"

She looked up at him evenly.

"If you think we have a fair chance to get the treasure and escape, I say let's risk it," she said firmly.

"Good!" he exclaimed. "Here we go!"

The little sphere slipped out of its cleft in the peak and dropped swiftly into the valley on the side opposite the Trap-Door City and its mysterious menace. Day was swiftly dying, and the lower passes of the mountains were already hazy with rapidly forming storm-clouds.

"Look!" cried Irma excitedly. "What are those things?"

Far in the distance a long line of wavering red lights snaked swiftly through the dusky valley toward them. Penrun picked up his binoculars.

"Spiders," he announced. "Scores of them. Each is carrying a sort of red torch. I have a feeling that those are what the monsters of the Trap-Door City have been waiting for."

He urged the sphere to swifter flight along the range. Miles from the Caves, he swept up over the peaks, and dropped down on the lowlands side. Dusk was deepening rapidly as he raced back toward the White River cataract under the pall of the gathering storm.

Among the boulders on the rough mountainside near the mouth of the Caves he eased the craft down to a gentle landing.

"Wait here," he told Irma. "I'll investigate and see if it is safe to enter the Caves."

They had seen the three men return to the ship, but others might have gone to the Caves after that. Penrun made his way down the slope to the lip of the cataract and the yawning blackness of the abysmal gorge below it.

Overhead the storm was gathering swiftly, and the saffron light of the dying day illuminated the plateau eerily. Half a mile away the Trap-Door City shimmered fantastically in the uncertain light. Penrun repressed a shudder. The Devil's own playground! Thank God, he and Irma would be out of it soon!

He crept down the narrow path that led under the ledge of the trickling cataract. Outside, a bolt of lightning stabbed down from the darkened heavens. Its lurid flash revealed the huge figure of a man, pistol in hand, beside the entrance to the Caves.

Too late to retreat now, even had he wished to. Penrun's weapon flashed first. A scream of pain and fury answered the flash, and the man's pistol clattered down on the rock. The next instant Penrun was helpless in the clutch of a mighty pair of arms that tried to squeeze the life out of him.

"Burn, me, will ye, ye dirty scum!" roared the giant of a man tightening his grip. "I'll break your damned back for ye and heave ye into the gorge!"

Penrun writhed frenziedly, trying to twist his pistol around against his enemy's back, while they struggled desperately about the ledge above the dizzy blackness of the gorge. But the pistol struck the wall beside the entrance and fell under their trampling feet.

Penrun was gasping in agony at the intolerable pain in his spine. Darting points of light danced before his eyes. Then from the opening in the rock showed a beam of white light and a man slowly emerged from the Caves. The grip on Penrun relaxed slightly as the man came toward the two combatants. Penrun could distinguish him closely now. A heavy, pasty face with liquid black eyes and a crown of thinning hair. Helgers! He was staggering and grunting under the weight of a heavy metal box.

"What's the matter, Borgain?" he asked.

"Got this bird, Penrun, we been waitin' for!"

"We don't need him, now that we already have the treasure. Still, it's a good thing we found him. Just as well to have no tales circulating about the Universe about our find. Toss him into the gorge, and go down and watch the other three chests until I get—"

"Dick, Dick!" Irma's excited voice floated down from up among the boulders. "The spiders with those red cylinder torches have arrived! They are attacking the Osprey!"

Helgers jerked up his head.

"Why, if it isn't the little spitfire!" he exclaimed in pleased astonishment. "I thought the damned spiders had eaten her long before this. Rather changes things, Borgain. I'll just go on up and let my little playmate know I am here. Toss our friend over the edge there, and bring up another treasure chest."

"What was that she was sayin' about the spiders attackin' the Osprey?" Borgain's voice was anxious.

"Oh, that's nothing the boys can't handle," said Helgers confidently. "In case they don't, we'll have to feel sorry for them and take our friend's sphere. Only have to split the treasure two ways, in that case," he added, moving up the slope.

Borgain's answer was a grunt of surprise, for his captive had squirmed suddenly out of his clutch. The big man plunged forward recklessly with arms outstretched in the groping darkness. Penrun, desperately remembering the sickening drop at their feet to the pool three thousand feet below, backed against the rock.

A flash of lightning. Borgain's ape-like arms were nearing him. Penrun lashed out at the darkened features. His knuckles bit deep into the flesh. He slipped aside as Borgain, mouthing fearful curses, rammed into the rock wall and rebounded.

Again the fumbling search. Another lightning flash. Penrun struck with frenzied desperation. Borgain took the blow behind the ear and staggered. He whirled, wild with fury, and charged vainly along the narrow ledge.

"I'll get ye this time, damn your dirty carcass—ugh!"

Guided by the sound of his voice, Penrun struck with all his strength. Borgain's nose flattened under the blow. He whirled half around.

"I'll kill ye! I'll kill—help, help—a-ah!"

Lost in the blackness he had plunged over the lip of the rock, thinking he was charging Penrun. Down into the yawning gorge his body hurtled, the sound of his frenzied, dwindling screams floating up eerily out of the black, ominous depths.

Penrun crouched against the wall, sick and trembling. Irma, Helgers! He must hurry! He fumbled again for the pistols. They were gone. Crawling forward now, still shaken by his narrow escape from death, he gained the pathway. The rain was drumming wildly on the barren granite now, and the pitch-blackness was shattered only by ghastly lightning bolts.

Guided by the flashes, he clambered up the slope and halted abruptly. The door of the space-sphere was open, and, silhouetted against the soft glow of light within it, was Irma, seated dejectedly with bowed head, heedless of the cold rain beating down upon her. Helgers was nowhere to be seen. Penrun dashed forward.

"Irma, Irma!" he cried. "What has happened? Where is he?"

She raised her head slowly and stared at him as at one risen from the dead. Then she burst into tears.

"He said they had killed you—had thrown your body into the gorge," she sobbed. "I—I just didn't want to live after that. Are you hurt?"

"Not a bit," he assured her fervently. "But where is Helgers?"

"I pistoled him," she said quietly. "I had no choice. He came at me after I warned him to keep away. He fell over there among the rocks. Oh, Dick, let us hurry away from this mad place!"

He stared at the rain-swept rocks. The heavy metal treasure chest lay a few yards away where Helgers had dropped it. Penrun moved cautiously toward the spot where he had fallen. He was gone. The rain had washed away any traces of blood that might have remained.

While Penrun hesitated, the roar of the tempest was split by a man's scream of agony. A lurid flash of lightning an instant later revealed a gigantic spider down by the cataract with Helgers' struggling body in his mandible jaws. Returning blackness blotted out the scene.

Irma's pistol stabbed a ray through the driving rain at the hideous monster. Instantly its grating roar for help rang out, and a group of red lights from the doomed Osprey across the plateau, detached themselves from the others and came streaking for the cataract.

Penrun seized the heavy treasure chest and staggered to the sphere.

"Hurry, here they come!" screamed the girl.

He fell through the door with his burden just as the foremost monster leaped the river. The next instant Irma sent the sphere rocketing upward. Just before they plunged into the clouds they caught a last glimpse of the Osprey with her ray guns melted off by the red cylinder torches, and great holes gaping in her sides through which the monsters were carrying out the members of the crew to their cavern of the Living Dead.

As the sphere burst through the storm cloud into the frigid air above it, Irma gave a cry and pointed at the peak where they had hidden in the sphere. The peak was now alive with moving red lights of monsters searching vainly for them. The scene dropped swiftly below as the sphere gathered speed for its homeward journey.

"We got only a small portion of the treasure, but it will be enough," said Penrun. "After we pay your family's debt, I want to spend a hundred thousand or so for a specially chartered battle-sphere which will come back here to Titan. If the Interplanetary Council will do nothing about the Trap-Door City, I shall, independently. Not rays, but good old primitive bombs such as they used back in the Twentieth Century. I'll blow the hellish place off the face of the map and with it the cavern of the Living Dead. I think those lying in the hammocks would thank me for releasing them in that way."