board. It was a Ganymedan who hadtreacherously attacked him. The puzzle was slowly fitting its piecestogether. But the major piece still eluded him. What would happen tothe ship?

  As he turned to go back to his room, a ripping, tearing, grindingsound came to his startled ears. It was followed by a sudden swishingnoise. Grant knew what that meant. A meteor had ripped into the vitalsof the space-flier, and the precious air was rushing through thefissure into outer space. He whirled without an instant's hesitationand sprang down the long corridor toward the captain's quarters. Ifcaught in time, the hole could be plugged.

  Even as he ran, there was another grinding smash, then another, andanother. Good Lord, they must have headed right into a meteor shower.Panels were sliding open, and people, scantily attired, thruststartled heads out into the corridor. Someone called after him, but hedid not heed or stop his headlong race. He must get to the controlroom at once.

  Already the air in the corridor was a sucking whirlpool that beat andeddied about him in its mad rush to escape. It sounded like thedrumbeat of unsilenced exploders. A meteor shower of unprecedentedproportions! In the back of Grant's mind as he ran, hammered athought. Every swarm of meteors in the solar system was carefullyplotted. The lanes of travel were routed to avoid them. There was noknown shower in this particular area!

  He collided violently with a strange ungainly figure. In his desperatehaste he did not give much heed, but tried to push his way past. Thefigure turned on him, and then Grant stopped short, an exclamationfrozen to his lips. Red unwinking eyes stared out at him from gogglesset in a helmet. The body was completely inclosed in lusterlesscreatoid. It was a Ganymedan in a space-suit!

  * * * * *

  Grant saw the quick movement of the other toward an open side flap. Hedid not hesitate an instant. His fist shot out and caught theGanymedan flush in the throat, while his left hand simultaneouslyseized the creatoid-covered arm that gripped a pencil-ray. Thehelmeted head went back with a sickening thud. But the Ganymedan wasa powerful brute. Even as he staggered back from the force of theblow, vainly trying to release the pencil-ray for action, his rightfoot jerked forward. The next moment both were rolling on the floor,twisting and heaving in silent combat. Frightened passengers rusheddown the corridor, screaming with terror, half carried along by thehurricane wind, clambering over the combatants in an insane desire toget away, where, they knew not; and still neither relaxed his grip,seeking a mortal hold.

  Pemberton was certain that his silent unknown foe held the clue to themystery he was trying to fathom. He fought on, silently, grimly. Thecold creatoid fabric was slippery, but a sudden jerk of an arm, acertain quick twist that Grant was familiar with, and his enemy wentlimp. Grant's breath was coming in quick, labored gasps. There wasvery little air left now. But he did not care. He tugged at thefastenings on the helmet. He must see who his captive was, wrest fromhim the heart of the mystery.

  There came a clatter of feet behind him, a sudden rush of space-suitedfigures that overwhelmed and passed over him with trampling strides.He was torn loose from his prey, rolled over and over, gasping forair. When he staggered to his feet again, bruised and shaken, thecorridor was swept clean of figures. His assailants had carried hisopponent away with them.

  A wild surge of anger swept through him. More Ganymedans, theserescuers, all accoutered for airless space. They had been carefullyprepared for this. Heedless of all else, he swayed groggily afterthem, intent only on joining battle once again. The illumination wasdim now, the cries of fear that had rung through the ship were gone;only a deathly silence reigned now. His lungs were burning for wantof air; even the whirlwind had died down for lack of fuel. But stillhe kept on, like a bloodhound on the trail.

  * * * * *

  He rounded a corner. A slight figure, swaying like a reed, collidedwith him and would have fallen if he had not thrust out a supportingarm. It was a girl. Even in the shadowy light he saw that she wasbeautiful. Her delicately molded features were drained white, but herdeep pooled eyes were level in their gaze, unafraid.

  "I'm sorry," he managed, finding utterance labored, "Are you hurt?"

  "Quite all right," she said, with a wan smile, "if only I had some airto breathe."

  The essential bravery of her touched him. He forgot all about theescaped Ganymedans.

  "We'll have to try some other portion of the ship. Maybe some of thebulkheads are uninjured."

  She shook her head. "I just saw the captain," she enunciated faintly."Every bulkhead is riddled. Said--I--should get space-suit--instateroom--though no use--doomed. Something wrong--wireless--notworking...." Her voice trailed. She had fainted.

  Grant caught up her slight form and lurched unsteadily into thenearest cabin. The blood was roaring in his ears now, his heart waspumping madly, but he forced himself on. His eyes strained toward thecompartment where the emergency space-suit was neatly compacted. ThankGod. It was still there. The inmate had evidently rushed out at thefirst alarm to join the terror-maddened crush.

  Pemberton worked with feverish haste. Somehow he thrust theunconscious girl into the suit, tightened the helmet into position,opened the valve that started the steady measured flow of life-givingoxygen. Then, with dark spots dancing before his eyes, he depositedher gently on the floor, and managed to force himself in the nowalmost total darkness toward another room.

  * * * * *

  His swelling hands fumbled. The compartment was empty. Despairing,conscious only of a desire to lie down, to rest, he tried another. It,too, was empty. He stumbled over sprawled bodies, fell, managed to getup again. Again he fumbled into a compartment. The clammy feel of thecreatoid never was more welcome. His breath was coming in whistlinggasps. It seemed ages of strangulation before the first cool rush ofoxygen expanded his tortured lungs. For a full minute he stood there,inhaling deep draughts. Then once more he was himself, his brainfunctioning with keen clarity.

  He must find the Ganymedans and come to grips with them. There was nodoubt in his mind that somehow they had been responsible for thecataclysm. Just how, he did not know, but he would find out.

  But the girl. He could not leave her. Duty and something else stirredinto conflict. He hesitated. In the flap of the suit was an emergencyflash. Throwing the beam on the walls and flooring, he managed toretrace his steps to the cabin where he had left her. As he flashed itinside, his heart gave a great bound. She was standing now.

  "Feel all right?" he spoke into the tiny transmitter that was part ofthe regulation equipment.

  "Fine." Her warm, rich voice spoke in his ear. "But I'm not thinkingof myself. Are the others on board safe? What happened?"

  "I'm afraid we are the only ones alive," he told her gravely. "As towhat happened, I can only guess. We seem to have hit an unusuallyheavy meteor shower that riddled us through and through, though--" Hepaused.

  "Though what?"

  He ignored her question. "The first thing we've got to do is find outwhere we are." His flash sought the window switch and found it. Hewent over and pressed it. A section of the beryllium-steel casing slidsmoothly open, disclosing a thick flawless quartzite port. He staredout at the dark pattern of space. Long he gazed, then a stifledexclamation reached the girl.

  "What is it?" she cried.

  "Come and look," he told her gravely, and made room for her.

  * * * * *

  At first she saw only the unwinking stars of space. Then her eyesshifted forward. Jupiter lay ahead, a vast cloud-girt disk. It wasominously near. Somehow it gave the effect of rushing straight at her.

  Right along the equator floated, or seemed to float, a huge redoval--the Great Red Spot of Jupiter. She had heard of it before. Butwhat caught her immediate attention was a tiny flare of intenseillumination, right in the very heart of the Spot. Bright orange itwas, tinged with yellow, dazzling even at this distance. She watchedit eagerly. Then she gave a sudden start.

  "You've seen it
." Grant's voice sounded quietly in her helmet.

  "Yes. Why, it--it pulsates!"

  "Exactly. Now look along the hull of the ship."

  She did so, and gasped again. The steel-shod sides were bathed in anunearthly orange glow.

  "Why, that must be the light from the orange spot down there."

  Grant nodded. "Yes, and more than that. They are power waves of anature that we've known nothing of before. We are being pulled downalong that beam straight for Jupiter, straight for the source of thatlight!"

  "But that means there are intelligent beings on Jupiter."

  "No doubt."

  "But--but everyone know that there's no life on Jupiter. It's a frozenwaste swathed in impenetrable whirlwind clouds."

  "How does everyone know?" Grant retorted. "Has anyone ever penetratedthrough