document: THE LOST TRIBES OF VENUS
   
  
   By ERIK FENNEL
   
   On mist-shrouded Venus, where hostile swamp meets hostile sea ... there did Barry Barr—Earthman transmuted—swap his Terran heritage for the deep dark waters of Tana; for the strangely beautiful Xintel of the blue-brown skin.
   
   
   [Transcriber's Note: This etext was produced from Planet Stories May 1954. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.]
   
   
   
   Evil luck brought the meteorite to those particular space-time coordinates as Number Four rode the downhill spiral toward Venus. The football-sized chunk of nickel-iron and rock overtook the ship at a relative speed of only a few hundred miles per hour and passed close enough to come within the tremendous pseudo-gravatic fields of the idling drivers.
   
   It swerved into a paraboloid course, following the flux lines, and was dragged directly against one of the three projecting nozzles. Energy of motion was converted to heat and a few meteoric fragments fused themselves to the nonmetallic tube casing.
   
   In the jet room the positronic line accelerator for that particular driver fouled under the intolerable overload, and the backsurge sent searing heat and deadly radiation blasting through the compartment before the main circuit breakers could clack open.
   
   The bellow of the alarm horn brought Barry Barr fully awake, shattering a delightfully intimate dream of the dark haired girl he hoped to see again soon in Venus Colony. As he unbuckled his bunk straps and started aft at a floating, bounding run his weightlessness told him instantly that Number Four was in free fall with dead drivers.
   
   Red warning lights gleamed wickedly above the safety-locked jet room door, and Nick Podtiaguine, the air machines specialist, was manipulating the emergency controls with Captain Reno at his elbow. One by one the crew crowded into the corridor and watched in tense silence.
   
   The automatic lock clicked off as the jet room returned to habitable conditions, and at Captain Reno's gesture two men swung the door open. Quickly the commander entered the blasted jet room. Barry Barr was close behind him.
   
   Robson Hind, jet chief of Four and electronics expert for Venus Colony, hung back until others had gone in first. His handsome, heavy face had lost its usual ruddiness.
   
   Captain Reno surveyed the havoc. Young Ryan's body floated eerily in the zero gravity, charred into instant death by the back-blast. The line accelerator was a shapeless ruin, but except for broken meter glasses and scorched control handles other mechanical damage appeared minor. They had been lucky.
   
   "Turnover starts in six hours twelve minutes," the captain said meaningfully.
   
   Robson Hind cleared his throat. "We can change accelerators in two hours," he declared. With a quick reassumption of authority he began to order his crew into action.
   
   It took nearer three hours than two to change accelerators despite Hind's shouted orders.
   
   At last the job was completed. Hind made a final check, floated over to the control panel and started the fuel feed. With a confident smile he threw in the accelerator switch.
   
   The meter needles climbed, soared past the red lines without pausing, and just in time to prevent a second blowback, Hind cut the power.
   
   " There's metal in the field! " His voice was high and unsteady.
   
   
  
   
   Everyone knew what that meant. The slightest trace of magnetic material would distort the delicately balanced cylinder of force that contained and directed the Hoskins blast, making it suicidal to operate.
   
   Calmly Captain Reno voiced the thought in every mind.
   
   "It must be cleared. From the outside."
   
   Several of the men swore under their breaths. Interplanetary space was constantly bombarded, with an intensity inverse to the prevailing gravitation, by something called Sigma radiation. Man had never encountered it until leaving Earth, and little was known of it except that short exposure killed test animals and left their bodies unpredictably altered.
   
   Inside the ship it was safe enough, for the sleek hull was charged with a Kendall power-shield, impervious to nearly any Sigma concentration. But the shielding devices in the emergency spacesuits were small and had never been space-tested in a region of nearly equalized gravitations.
   
   The man who emerged from the airlock would be flipping a coin with a particularly unpleasant form of death.
   
   Many pairs of eyes turned toward Robson Hind. He was jet chief.
   
   "I'm assigned, not expendable," he protested hastily. "If there were more trouble later...." His face was pasty.
   
   Assigned. That was the key word. Barry Barr felt a lump tightening in his stomach as the eyes shifted to him. He had some training in Hoskins drivers. He knew alloys and power tools. And he was riding Four unassigned after that broken ankle had made him miss Three. He was the logical man.
   
   "For the safety of the ship." That phrase, taken from the ancient Earthbound code of the sea, had occurred repeatedly in the indoctrination manual at Training Base. He remembered it, and remembered further the contingent plans regarding assigned and unassigned personnel.
   
   For a moment he stood indecisively, the nervous, unhumorous smile quirking across his angular face making him look more like an untried boy than a structural engineer who had fought his way up through some of the toughest tropical construction camps of Earth. His lean body, built more for quick, neatly coordinated action than brute power, balanced handily in the zero gravity as he ran one hand through his sandy hair in a gesture of uncertainty.
   
   He knew that not even the captain would order him through the airlock.
   
   But the members of the Five Ship Plan had been selected in part for a sense of responsibility.
   
   "Nick, will you help me button up?" he asked with forced calmness.
   
   For an instant he thought he detected a sly gleam in Hind's eyes. But then the jet chief was pressing forward with the others to shake his hand.
   
   Rebellious reluctance flared briefly in Barry's mind. Dorothy Voorhees had refused to make a definite promise before blasting off in Three—in fact he hadn't even seen her during her last few days on Earth. But still he felt he had the inside track despite Hind's money and the brash assurance that went with it. But if Hind only were to reach Venus alive—
   
   
  
   
   The blazing disc of Sol, the minor globes of the planets, the unwinking pinpoints of the stars, all stared with cosmic disinterest at the tiny figure crawling along the hull. His spacesuit trapped and amplified breathing and heartbeats into a roaring chaos that was an invitation to blind panic, and all the while there was consciousness of the insidiously deadly Sigma radiations.
   
   Barry found the debris of the meteorite, an ugly shining splotch against the dull superceramic tube, readied his power chisel, started cutting. Soon it became a tedious, torturingly strenuous manual task requiring little conscious thought, and Barry's mind touched briefly on the events that had brought him here.
   
   First Luna, and that had been murderous. Man had encountered Sigma for the first time, and many had died before the Kendall-shield was perfected. And the chemical-fueled rockets of those days had been inherently poor.
   
   Hoskins semi-atomics had made possible the next step—to Mars. But men had found Mars barren, swept clear of all life in the cataclysm that had shattered the trans-Martian planet to form the Asteroid Belt.
   
   Venus, its true surface forever hidden by enshrouding mists, had been well within one-way range. But Hoskins fuel requirements for a round trip added up to something beyond critical mass. Impossible.
   
   But the Five Ship Plan had evolved, a joint enterprise of government and various private groups. Five vessels were to go out, each fueled to within a whiskered neutron of spontaneous detonation, manned by specialists who, it was hoped, could maintain themselves under alien conditions.
   
   On Venus the leftover fuel from all five would be transferred to whichever ship had survived the outbound voyage in best condition. That one would return to Earth. Permanent base or homeward voyage with colonists crowded aboard like defeated sardines? Only time would tell.
   
   Barry Barr had volunteered, and because the enlightened guesses of the experts called for men and women familiar with tropical conditions, he had survived the rigorous weeding-out process. His duties in Venus Colony would be to refabricate the discarded ships into whatever form was most needed—most particularly a launching ramp—and to study native Venusian materials.
   
   Dorothy Voorhees had signed on as toxicologist and dietician. When the limited supply of Earth food ran out the Colony would be forced to rely upon Venusian plants and animals. She would guard against subtle delayed-action poisons, meanwhile devising ways of preparing Venusian materials to suit Earth tastes and digestions.
   
   Barry had met her at Training Base and known at once that his years of loneliness had come to an end.
   
   She seemed utterly independent, self-contained, completely intellectual despite her beauty, but Barry had not been deceived. From the moment of first meeting he had sensed within her deep springs of suppressed emotion, and he had understood. He too had come up the hard way, alone, and been forced to develop a shell of hardness and cold, single-minded devotion to his work. Gradually, often unwillingly under his insistence, her aloofness had begun to melt.
   
   But Robson Hind too had been attracted. He was the only son of the business manager of the great Hoskins Corporation which carried a considerable share in the Five Ship Plan. Dorothy's failure to virtually fall into his arms had only piqued his desires.
   
   The man's smooth charm had fascinated the girl and his money had opened to her an entirely new world of lavish nightclubs and extravagantly expensive entertainments, but her inborn shrewdness had sensed some factor in his personality that had made her hesitate.
   
   Barry had felt a distrust of Hind apart from the normal dislike of rivalry. He had looked forward to being with Dorothy aboard Three, and had made no secret of his satisfaction when Hind's efforts to have himself transferred to Three also or the girl to Four had failed.
   
   But then a scaffold had slipped while Three was being readied, and with a fractured ankle he had been forced to miss the ship.
   
   He unclipped the magnetic detector from his belt and ran it inch by inch over the nozzle. He found one spot of metal, pinhead-sized, but enough to cause trouble, and once more swung his power chisel into stuttering action.
   
   Then it was done.
   
   As quickly as possible he inched back to the airlock. Turnover had to start according to calculations.
   
   
  
   
   Barry opened his eyes. The ship was in normal deceleration and Nick Podtiaguine was watching him from a nearby bunk.
   
   "I could eat a cow with the smallpox," Barry declared.
   
   Nick grinned. "No doubt. You slept around the clock and more. Nice job of work out there."
   
   Barry unhitched his straps and sat up.
   
   "Say," he asked anxiously. "What's haywire with the air?"
   
   Nick looked startled. "Nothing. Everything checked out when I came off watch a few minutes ago."
   
   Barry shrugged. "Probably just me. Guess I'll go see if I can mooch a handout."
   
   He found himself a hero. The cook was ready to turn the galley inside out while a radio engineer and an entomologist hovered near to wait on him. But he couldn't enjoy the meal. The sensations of heat and dryness he had noticed on awakening grew steadily worse. It became difficult to breathe.
   
   He started to rise, and abruptly the room swirled and darkened around him. Even as he sank into unconsciousness he knew the answer.
   
   The suit's Kendall-shield had leaked!
   
   Four plunged toward Venus tail first, the Hoskins jets flaring ahead. The single doctor for the Colony had gone out in Two and the crewmen trained in first aid could do little to relieve Barry's distress. Fainting spells alternated with fever and delirium and an unquenchable thirst. His breathing became increasingly difficult.
   
   A few thousand miles out Four picked up a microbeam. A feeling of exultation surged through the ship as Captain Reno passed the word, for the beam meant that some Earthmen were alive upon Venus. They were not necessarily diving straight toward oblivion. Barry, sick as he was, felt the thrill of the unknown world that lay ahead.
   
   Into a miles-thick layer of opacity Four roared, with Captain Reno himself jockeying throttles to keep it balanced on its self-created support of flame.
   
   "You're almost in," a voice chanted into his headphones through crackling, sizzling static. "Easy toward spherical one-thirty. Hold it! Lower. Lower. CUT YOUR POWER!"
   
   The heavy hull dropped sickeningly, struck with a mushy thud, settled, steadied.
   
   Barry was weak, but with Nick Podtiaguine steadying him he was waiting with the others when Captain Reno gave the last order.
   
   "Airlock open. Both doors."
   
   Venusian air poured in.
   
   "For this I left Panama?" one of the men yelped.
   
   "Enough to gag a maggot," another agreed with hand to nose.
   
   It was like mid-summer noon in a tropical mangrove swamp, hot and unbearably humid and overpowering with the stench of decaying vegetation.
   
   But Barry took one deep breath, then another. The stabbing needles in his chest blunted, and the choking band around his throat loosened.
   
   The outer door swung wide. He blinked, and a shift in the encompassing vapors gave him his first sight of a world bathed in subdued light.
   
   Four had landed in a marsh with the midships lock only a few feet above a quagmire surface still steaming from the final rocket blast. Nearby the identical hulls of Two and Three stood upright in the mud. The mist shifted again and beyond the swamp he could see the low, rounded outlines of the collapsible buildings Two and Three had carried in their cargo pits. They were set on a rock ledge rising a few feet out of the marsh. The Colony!
   
   Men were tossing sections of lattice duckboard out upon the swamp, extending a narrow walkway toward Four's airlock, and within a few minutes the new arrivals were scrambling down.
   
   Barry paid little attention to the noisy greetings and excited talk. Impatiently he trotted toward the rock ledge, searching for one particular figure among the men and women who waited.
   
   "Dorothy!" he said fervently.
   
   Then his arms were around her and she was responding to his kiss.
   
   Then unexpected pain tore at his chest. Her lovely face took on an expression of fright even as it wavered and grew dim. The last thing he saw was Robson Hind looming beside her.
   
   By the glow of an overhead tubelight he recognized the kindly, deeply lined features of the man bending over him. Dr. Carl Jensen, specialist in tropical diseases. He tried to sit up but the doctor laid a restraining hand on his shoulder.
   
   "Water!" Barry croaked.
   
   The doctor held out a glass. Then his eyes widened incredulously as his patient deliberately drew in a breath while drinking, sucking water directly into his lungs.
   
   "Doctor," he asked, keeping his voice low to spare his throat. "What are my chances? On the level."
   
   Dr. Jensen shook his head thoughtfully. "There's not a thing—not a damned solitary thing—I can do. It's something new to medical science."
   
   Barry lay still.
   
   "Your body is undergoing certain radical changes," the doctor continued, "and you know as much—more about your condition than I do. If a normal person who took water into his lungs that way didn't die of a coughing spasm, congestive pneumonia would get him sure. But it seems to give you relief."
   
   Barry scratched his neck, where a thickened, darkening patch on each side itched infuriatingly.
   
   "What are these changes?" he asked. "What's this?"
   
   "Those things seem to be—" the doctor began hesitantly. "Damn it, I know it sounds crazy but they're rudimentary gills."
   
   Barry accepted the outrageous statement unemotionally. He was beyond shock.
   
   "But there must be—"
   
   Pain struck again, so intense his body twisted and arched involuntarily. Then the prick of a needle brought merciful oblivion.
   
   
  
   II
   
   Barry's mind was working furiously. The changes the Sigma radiations had inflicted upon his body might reverse themselves spontaneously, Dr. Jensen had mentioned during a second visit—but for that to happen he must remain alive. That meant easing all possible strains.
   
   When the doctor came in again Barry asked him to find Nick Podtiaguine. Within a few minutes the mechanic appeared.
   
   "Cheez, it's good to see you, Barry," he began.
   
   "Stuff it," the sick man interrupted. "I want favors. Can do?"
   
   Nick nodded vigorously.
   
   "First cut that air conditioner and get the window open."
   
   Nick stared as though he were demented, but obeyed, unbolting the heavy plastic window panel and lifting it aside. He made a face at the damp, malodorous Venusian air but to Barry it brought relief.
   
   It was not enough, but it indicated he was on the right track. And he was not an engineer for nothing.
   
   "Got a pencil?" he asked.
   
   He drew only a rough sketch, for Nick was far too competent to need detailed drawings.
   
   "Think you can get materials?"
   
   Nick glanced at the sketch. "Hell, man, for you I can get anything the Colony has. You saved Four and everybody knows it."
   
   "Two days?"
   
   Nick looked insulted.
   
   He was back in eight hours, and with him came a dozen helpers. A power line and water tube were run through the metal partition to the corridor, connections were made, and the machine Barry had sketched was ready.
   
   Nick flipped the switch. The thing whined shrilly. From a fanshaped nozzle came innumerable droplets of water, droplets of colloidal size that hung in the air and only slowly coalesced into larger drops that fell toward the metal floor.
   
   Barry nodded, a smile beginning to spread across his drawn features.
   
   "Perfect. Now put the window back."
   
   Outside lay the unknown world of Venus, and an open, unguarded window might invite disaster.
   
   A few hours later Dr. Jensen found his patient in a normal sleep. The room was warm and the air was so filled with water-mist it was almost liquid. Coalescing drops dripped from the walls and curving ceiling and furniture, from the half clad body of the sleeping man, and the scavenger pump made greedy gulping sounds as it removed excess water from the floor.
   
   The doctor shook his head as he backed out, his clothes clinging wet from the short exposure.
   
   It was abnormal.
   
   But so was Barry Barr.
   
   With breathing no longer a continuous agony Barry began to recover some of his strength. But for several days much of his time was spent in sleep and Dorothy Voorhees haunted his dreams.
   
   Whenever he closed his eyes he could see her as clearly as though she were with him—her face with the exotic high cheek-bones—her eyes a deep gray in fascinating contrast to her raven hair—lips that seemed to promise more of giving than she had ever allowed herself to fulfil—her incongruously pert, humorous little nose that was a legacy from some venturesome Irishman—her slender yet firmly lithe body.
   
   After a few days Dr. Jensen permitted him to have visitors. They came in a steady stream, the people from Four and men he had not seen since Training Base days, and although none could endure his semi-liquid atmosphere more than a few minutes at a time Barry enjoyed their visits.
   
   But the person for whom he waited most anxiously did not arrive. At each knock Barry's heart would leap, and each time he settled back with a sigh of disappointment. Days passed and still Dorothy did not come to him. He could not go to her, and stubborn pride kept him from even inquiring. All the while he was aware of Robson Hind's presence in the Colony, and only weakness kept him from pacing his room like a caged animal.
   
   Through his window he could see nothing but the gradual brightening and darkening of the enveloping fog as the slow 82-hour Venusian day progressed, but from his visitors' words he learned something of Venusian conditions and the story of the Colony.
   
   Number One had bumbled in on visual, the pilot depending on the smeary images of infra-sight goggles. An inviting grassy plain had proved to be a layer of algae floating on quicksand. Frantically the crew had blasted down huge balsa-like marsh trees, cutting up the trunks with flame guns to make crude rafts. They had performed fantastic feats of strength and endurance but managed to salvage only half their equipment before the shining nose of One had vanished in the gurgling ooze.
   
   Lost in a steaming, stinking marsh teeming with alien creatures that slithered and crawled and swam and flew, blinded by the eternal fog, the crew had proved the rightness of their choice as pioneers. For weeks they had floundered across the deadly terrain until at last, beside a stagnant-looking slough that drained sluggishly into a warm, almost tideless sea a mile away, they had discovered an outcropping of rock. It was the only solid ground they had encountered.
   
   One man had died, his swamp suit pierced by a poisonous thorn, but the others had hand-hauled the radio beacon piece by piece and set it up in time to guide Two to a safe landing. Houses had been assembled, the secondary power units of the spaceship put to work, and the colony had established a tenuous foothold.
   
   Three had landed beside Two a few months later, bringing reinforcements, but the day-by-day demands of the little colony's struggle for survival had so far been too pressing to permit extended or detailed explorations. Venus remained a planet of unsolved mysteries.
   
   The helicopter brought out in Three had made several flights which by radar and sound reflection had placed vague outlines on the blank maps. The surface appeared to be half water, with land masses mainly jungle-covered swamp broken by a few rocky ledges, but landings away from base had been judged too hazardous.
   
   Test borings from the ledge had located traces of oil and radioactive minerals, while enough Venusian plants had proven edible to provide an adequate though monotonous food source.
   
   Venus was the diametric opposite of lifeless Mars. Through the fog gigantic insects hummed and buzzed like lost airplanes, but fortunately they were harmless and timid.
   
   In the swamps wildly improbable life forms grew and reproduced and fought and died, and many of those most harmless in appearance possessed surprisingly venomous characteristics.
   
   The jungle had been flamed away in a huge circle around the colony to minimize the chances of surprise by anything that might attack, but the blasting was an almost continuous process. The plants of Venus grew with a vigor approaching fury.
   
   Most spectacular of the Venusian creatures were the amphibious armored monsters, saurian or semi-saurians with a slight resemblance to the brontosauri that had once lived on Earth, massive swamp-dwellers that used the slough beside the colony's ledge as a highway. They were apparently vegetarians, but thorough stupidity in tremendous bulk made them dangerous. One had damaged a building by blundering against it, and since then the colony had remained alert, using weapons to repel the beasts.
   
   The most important question—that of the presence or absence of intelligent, civilized Venusians—remained unanswered. Some of the men reported a disquieting feeling of being watched, particularly when near open water, but others argued that any intelligent creatures would have established contact.
   
   
  
   
   Barry developed definite external signs of what the Sigma radiation had done to him. The skin between his fingers and toes spread, grew into membranous webs. The swellings in his neck became more pronounced and dark parallel lines appeared.
   
   But despite the doctor's pessimistic reports that the changes had not stopped, Barry continued to tell himself he was recovering. He had to believe and keep on believing to retain sanity in the face of the weird, unclassifiable feelings that surged through his body. Still he was subject to fits of almost suicidal depression, and Dorothy's failure to visit him did not help his mental condition.
   
   Then one day he woke from a nap and thought he was still dreaming. Dorothy was leaning over him.
   
   "Barry! Barry!" she whispered. "I can't help it. I love you even if you do have a wife and child in Philadelphia. I know it's wrong but all that seems so far away it doesn't matter any more." Tears glistened in her eyes.
   
   "Huh?" he grunted. "Who? Me?"
   
   "Please, Barry, don't lie. She wrote to me before Three blasted off—oh, the most piteous letter!"
   
   Barry was fully awake now. "I'm not married. I have no child. I've never been in Philadelphia," he shouted. His lips thinned.
  "I—think—I—know—who—wrote—that—letter!" he declared grimly.
   
   "Robson wouldn't!" she objected, shocked, but there was a note of doubt in her voice.
   
   Then she was in his arms, sobbing openly.
   
   "I believe you, Barry."
   
   She stayed with him for hours, and she had changed since the days at Training Base. Long months away from the patterned restraints of civilization, living each day on the edge of unknown perils, had awakened in her the realization that she was a human being and a woman, as well as a toxicologist.
   
   When the water-mist finally forced her departure she left Barry joyous and confident of his eventual recovery. For a few minutes anger simmered in his brain as he contemplated the pleasure of rearranging Robson Hind's features.
   
   The accident with the scaffold had been remarkably convenient, but this time the ruthless, restless, probably psychopathic drive that had made Robson Hind more than just another rich man's spoiled son had carried him too far. Barry wondered whether it had been inefficiency or judiciously distributed money that had made the psychometrists overlook some undesirable traits in Hind's personality in accepting him for the Five Ship Plan.
   
   But even with his trickery Hind had lost.
   
   He slept, and woke with a feeling of doom.
   
   The slow Venusian twilight had ended in blackness and the overhead tubelight was off.
   
   He sat up, and apprehension gave way to burning torture in his chest.
   
   Silence! He fumbled for the light switch, then knelt beside the mist machine that no longer hummed. Power and water supplies were both dead, cut off outside his room.
   
   Floating droplets were merging and falling to the floor. Soon the air would be dry, and he would be choking and strangling. He turned to call for help.
   
   The door was locked!
   
   He tugged and the knob came away in his hand. The retaining screw had been removed.
   
   He beat upon the panel, first with his fists and then with the metal doorknob, but the insulation between the double alloy sheets was efficient soundproofing. Furiously he hurled himself upon it, only to bounce back with a bruised shoulder. He was trapped.
   
   Working against time and eventual death he snatched a metal chair and swung with all his force at the window, again, again, yet again. A small crack appeared in the transparent plastic, branched under continued hammering, became a rough star. He gathered his waning strength, then swung once more. The tough plastic shattered.
   
   He tugged at the jagged pieces still clinging to the frame. Fog-laden Venusian air poured in—but it was not enough!
   
   He dragged himself head first through the narrow opening, landed sprawling on hands and knees in the darkness. In his ears a confused rustling drone from the alien swamp mingled with the roar of approaching unconsciousness.
   
   There was a smell in his nostrils. The smell of water. He lurched forward at a shambling run, stumbling over the uneven ground.
   
   Then he plunged from the rocky ledge into the slough. Flashes of colored light flickered before his eyes as he went under. But Earth habits were still strong; instinctively he held his breath.
   
   Then he fainted. Voluntary control of his body vanished. His mouth hung slack and the breathing reflex that had been an integral part of his life since the moment of birth forced him to inhale.
   
   Bubbles floated upward and burst. Then Barry Barr was lying in the ooze of the bottom. And he was breathing, extracting vital oxygen from the brackish, silt-clouded water.
   
   
  
   III
   
   Slowly his racing heartbeat returned to normal. Gradually he became aware of the stench of decaying plants and of musky taints he knew instinctively were the scents of underwater animals. Then with a shock the meaning became clear. He had become a water-breather, cut off from all other Earthmen, no longer entirely human. His fellows in the colony were separated from him now by a gulf more absolute than the airless void between Earth and Venus.
   
   Something slippery and alive touched him near one armpit. He opened his eyes in the black water and his groping hand clutched something burrowing into his skin. With a shudder of revulsion he crushed a fat worm between his fingers.
   
   Then dozens of them—hundreds—were upon him from all sides. He was wearing only a pair of khaki pants but the worms ignored his chest to congregate around his face, intent on attacking the tender skin of his eyelids.
   
   For a minute his flailing hands fought them off, but they came in increasing numbers and clung like leeches. Pain spread as they bit and burrowed, and blindly he began to swim.
   
   Faster and faster. He could sense the winding banks of the slough and kept to midchannel, swimming with his eyes tightly closed. One by one the worms dropped off.
   
   He stopped, opened his eyes, not on complete darkness this time but on a faint blue-green luminescence from far below. The water was saltier here, and clearer.
   
   He had swum down the slough and out into the ocean. He tried to turn back, obsessed by a desire to be near the colony even though he could not go ashore without strangling, but he had lost all sense of direction.
   
   He was still weak and his lungs were not completely adjusted to underwater life. Again he grew dizzy and faint. The slow movements of hands and feet that held him just below the surface grew feeble and ceased. He sank.
   
   Down into dimly luminous water he dropped, and with his respiratory system completely water-filled there was no sensation of pressure. At last he floated gently to the bottom and lay motionless.
   
   Shouting voices awakened him, an exultant battle cry cutting through a gasping scream of anguish. Streaks of bright orange light were moving toward him in a twisting pattern. At the head of each trail was a figure. A human figure that weaved and swam in deadly moving combat. One figure drifted limply bottomward.
   
   Hallucination, Barry told himself. Then one of the figures broke from the group. Almost overhead it turned sharply downward and the feet moved in a powerful flutter-kick. A slender spear aimed directly at the Earthman.
   
   Barry threw himself aside. The spear point plunged deep into the sticky, yielding bottom and Barry grappled with its wielder.
   
   Pointed fingernails raked his cheek. Barry's balled fist swung in a roundhouse blow but water resistance slowed the punch to ineffectiveness. The creature only shook its head and came in kicking and clawing.
   
   Barry braced his feet against the bottom and leaped. His head butted the attacker's chest and at the same instant he lashed a short jab to the creature's belly. It slumped momentarily, its face working.
   
   Human—or nearly so—the thing was, with a stocky, powerful body and webbed hands and feet. A few scraps of clothing, seemingly worn more for ornament than covering, clung to the fishbelly-white skin. The face was coarse and savage.
   
   It shook off the effects of Barry's punch and one webbed hand snatched a short tube from its belt.
   
   Barry remembered the spring-opening knife in his pocket, and even as he flicked the blade out the tube-weapon fired. Sound thrummed in the water and the water grew milky with a myriad of bubbles. Something zipped past his head, uncomfortably close.
   
   Then Barry struck, felt his knife slice flesh and grate against bone. He struck again even as the undersea being screamed and went limp.
   
   Barry stared through the reddening water.
   
   Another figure plunged toward him. Barry jerked the dead Venusian's spear from the mud and raised it defensively.
   
   But the figure paid no attention. This one was a female who fled desperately from two men closing in from opposite sides. One threw his spear, using an odd pushing motion, and as she checked and dodged, the other was upon her from behind.
   
   One arm went around her neck in a strangler's hold, bending her slender body backward. Together captor and struggling captive sank toward the bottom. The other recovered his thrown spear and moved in to help secure her arms and legs with lengths of cord.
   
   One scooped up the crossbow the girl had dropped. The other ripped at her brief skirt and from her belt took a pair of tubes like the one the dead Venusian had fired at Barry, handling them as though they were loot of the greatest value. He jerked cruelly at the slender metallic necklace the girl wore but it did not break.
   
   He punched the helpless girl in the abdomen with the butt of his spear. The girl writhed but she did not attempt to cry out.
   
   Barry bounded toward them in a series of soaring leaps, knife and spear ready. One Venusian turned to meet him, grinning maliciously.
   
   Barry dug one foot into the bottom and sidestepped a spear thrust. His own lunge missed completely. Then he and the Venusian were inside each other's spear points, chest to chest. A pointed hook strapped to the inside of the creature's wrist just missed Barry's throat. The Earthman arched his body backward and his knife flashed upward. The creature gasped and pulled away, clutching with both hands at a gaping wound in its belly.
   
   The other one turned too late as Barry leaped.
   
   Barry's hilt cracked against its jawbone.
question_text: What is the plot of the story?
response: Barry Barr is a structural engineer serving on Number Four, a ship taking part in the Five Ship Plan headed for Venus. The Five Ship Plan had been designed to avoid filling one ship to critical mass with fuel; instead, five ships would fill their tanks as much as safely possible, land on Venus, and the ship that had sustained the least amount of damage would take on the fuel reserves of the other four for the return trip to Earth unless a successful colony could be established on Venus. Barry had originally been assigned to Number Three, but an ankle injury caused him to take the later ship. A meteorite strikes Number Four, and since Barry is unassigned and therefore expendable, he goes outside the ship to remove the debris in spite of the dangerous presence of Sigma radiation, which had been known to kill animals. As he is outside, he thinks about Dorothy Voorhees, a toxicologist on Number Three with whom Barry is in love. The wealthy jet chief Robson Hind is also in love with Dorothy, although Dorothy only has a shallow interest in what he has to offer. Barry's spacesuit offers minimal protection against the radiation, and when he returns, he discovers he has indeed developed a kind of sickness that causes him to struggle to breathe in the ship's air. When Number Four finally lands on Venus, Barry is surprised to discover he can breathe much easier in the thick, humid atmosphere there. As Number Four reconnects with the makeshift colony the previous ships have constructed, Barry is reunited with Dorothy briefly before passing out. Dr. Carl Jensen examines Barry and keeps him on bed rest for several days. When Barry awakens, he recruits his friend Nick to help him fashion a machine that will transfer the Venusian atmosphere into his room so that he may breathe easier. Dr. Jensen is shocked at the physical changes in Barry; over time, he grows gills and webbed feet. Finally, Dorothy visits him in his room and reveals her true love for him; she had been hesitant to do so because she had received a communication from his wife in Philadelphia revealing Barry was married with a child. This news surprises Barry since he is not married; Robson must have written the letter to drive a wedge between him and Dorothy. When Barry awakens the next day, he discovers his door is locked and the machine drawing Venusian air into his room has been shut off. Desperate to breathe, Barry breaks out of his room and jumps into the nearby slough, where he is attacked by hundreds of hostile worms. He swims further out into an ocean, amazed by his ability to breathe underwater. Underwater, Barry runs into two Venusians who attack him and a female Venusian. Barry helps her and saves himself by fighting off the attackers.