The map of the moon was not as complete as it could have been, either. No particular interest had been taken in our satellite since the first exploratory expeditions nearly fifty years before, when it had been determined that the moon was of no value to Earthmen, either as an outpost for colonization or a station for the production of power from the sun's rays. Jack did the best he could, however, and the little dots he placed on the map were close enough together to assure complete vaporization of the solid material in less than the allotted time.

At the end of the second day out, by earth-time, the dead satellite loomed immense, only five thousand miles ahead. Holden was in the pilot house when Edwards began turning on the deceleration tubes.

"I flashed your message to the other ships," he said, as his quick fingers touched the buttons which sent messages to the tube-room, "telling them to stand by and land with us. I understand that the plan is to use these ships to travel over the surface of the moon, making landings in such positions that expeditions can be sent out in four directions to plant cartridges. That will certainly give us plenty of time, if nothing goes wrong."

"I don't see what could go wrong," replied Holden, "since that madman is out of the way."

Eagerly he watched the dead, dust-covered surface approach, marveling at the huge craters and precipitous peaks.

In two hours the five thousand miles had been reduced to less than that many yards, and in a few more minutes the three great ships were settling softly on the smooth surface of the plain at the foot of Mount Julian.

Space suits were rapidly donned, the air-locks set in operation, and the men hastily began unloading the first four charges of hexoxen and Europium. Holden called a meeting of the ship commanders in the pilot room of the San Francisco.

"Commander Huges," he addressed the man in charge of the Los Angeles, "you will proceed toward Mount Locke, and continue in that line until you reach the spot marked on this chart, which is directly opposite our present position. Rogers, you take the Ganymede, and go at an angle of 120 degrees to Huges' course, toward Mount Zoga. I will continue over the Crater of Aristotle. We will keep in constant communication with each other by means of the space phone. Time the charges so that they will commence to react on the afternoon of the twenty-eighth, thus giving a sufficient margin of time in case of delays due to parties getting lost. That's all."

The Ganymede and the Los Angeles left almost immediately, while men from the San Francisco set out to plant the first charges. There were four men to each cartridge, since it was necessary that they travel fast.

Holden smiled as the lean figure of Professor Erickson, almost lost in his space-suit, bounded away in great leaps at the head of his party. In five hours they returned, having had no trouble at all. Edwards manipulated the controls, and the ship rose quickly to an altitude of about five thousand feet and headed for the rim of the Crater of Aristotle, barely visible in the distance. As they neared the rim, they rose higher and higher. The mammoth cliffs of black rock towered above them, and the meters registered a height of five miles as they passed through a crack in the cliffs and looked down on the level floor beneath them.

Suddenly Holden, who had been inspecting the country from one of the bow ports, uttered an exclamation of astonishment.

"A tiny ship is rising toward us from the floor of the crater, near the cliffs!"

There it was, a speck rapidly growing larger, headed straight for them, and gaining velocity with every foot it covered.

Edwards worked frantically with the controls, diving in a zig-zag path toward the strange craft. Captain Linet rushed in, carrying one of the light hexoxen guns. Holden hurried to help him place it in a specially designed aperture in the bow, while Erickson and the regular radio man endeavored to establish communications with the intruder. A voice suddenly spoke from their instrument.

"You will consider yourselves our captives. Land at once as close as possible to the white spot you see at the base of the cliff. If you do not obey instructions, we will ram you immediately."

"Don't reply for a moment," Holden commanded, focusing his glasses in the direction indicated. As the powerful lenses brought out every detail of the scene below, he paled visibly.

"What's the matter?" demanded Erickson.

"Matter enough," was the amazing reply. "We've run into a den of some bandits. They must be the fiends who have been preying on the Earth-Mars shipping!"

The tremendous speed of the dive had brought them so close that all could see, without the aid of binoculars, the great skeletons of wrecked ships piled up at the base of the precipice.

"Tell those rats to go to hell," snapped Holden, "and get in touch with our own ships; use code and tell them to get here as quickly as possible, prepared for a fight. Get near enough to this pirate ship to open on it with the hexoxen guns. Can you keep them from ramming us, Edwards?"

"I think so, for a time, at least."

The enemy's craft was now only a few hundred yards away, and Holden scrutinized it closely for any sign that might give a clue to the original builders or present owners. Not over a hundred and fifty feet in length, with no visible openings, it looked like a slightly fattened steel needle. Its stern tubes were of the ordinary type; they glowed red against the silvery background, as the enemy swooped and circled, trying to get into position for a final, crushing blow.

"Every man in space suits," Holden ordered. "Good work, Linet," he cried, as he saw a sudden pock-mark appear in the pirate's side, where the devastating hexoxen bullet had struck.

"They've certainly got thick plates," remarked the Captain, as another direct hit failed to do more than scratch the metal. "Probably heavier up in front, if they mean what they say about ramming. I'm going to concentrate on the stern."

The dull red surface of the moon, the black walls of the crater, and the twinkling stars of outer space mingled in a fantastic whirl as Edwards skilfully kept the San Francisco out of the enemy's reach, at the same time giving Linet and the men in the observation compartment sufficient opportunity to train their guns on vital spots. It was a hopeless game, though, for the smaller ship was incredibly fast.

Erickson straightened up from his position behind the operator of the space-phone. "We can't make any connections with either the Ganymede or the Los Angeles. Probably these pirates have developed a shield which, thrown around their victims, prevents any message from getting to the outside."

That looked bad. Erickson switched the receiver back to the wave-length of the enemy. A continual stream of taunts and threats came from the loudspeaker.

"Why don't you surrender?" the gruff voice barked. "You haven't a chance against us, but if you surrender you may be allowed to work with us, for your own benefit as well as ours."

"Go to hell," the formerly meek Erickson roared into the transmitter, surprised at his own rage.

Then finally, with a desperate dash, the tiny pirate ship darted in. Edwards did his best to swerve away from the needle-point, but in vain. There was a shattering crash; Holden felt himself hurled through the air, but his heavy space-suit saved him from being crushed as he hit the wall of the room. Edwards stayed with the controls, somehow, cursing savagely.

"Only a glancing blow, but it smashed all the main stern tubes, and evidently disabled the anti-gravitational shield transmitter. We're going down."

Holden dashed to a port and glanced out. A welcome sight met his eyes. The enemy, also injured, was heading for home as fast as his disabled engines permitted.

"Those hexoxen bombs must have weakened his plating, so that it sprang when he rammed us," Edwards exclaimed when he saw what was happening.

Slowly the San Francisco sank toward the red and black volcanic ash of the crater floor. A hasty inspection revealed that Edwards had been correct in his diagnosis of the trouble. Extensive repairs would be necessary before they could proceed, but, fortunately, no one was seriously hurt, and the main shell showed no signs of strains or leaks.

As soon as Edwards had brought them safely to rest on the ground, Holden called a council of war.

"From the way these chaps fight, it's evident that they have no weapons, other than the bow of their ship, and possibly some short-range ray pistols, or the still more antiquated guns using some form of explosive to expel metal bullets. As soon as the shadow of the cliff throws this section of the crater into darkness, I'm going to do a little exploring, and see if I can't find out where these rats hide, when they're not out in space. Linet, you throw a line of pickets around the ship; Edwards, get started on repairs, and Erickson, keep on trying to get in touch with our companions."

Scarcely had he finished speaking when the light began to fade, and in a few minutes it was pitch black. Refusing to take anyone along with him, Holden crept out of the air-lock, and with an occasional glance at the compass fastened inside his suit, always pointing toward the San Francisco, he set out in the general direction of the wrecked space ships he had seen piled along the base of the cliff. He made good time, despite the weight of his suit and the poor footing afforded by the loosely piled dust, and finally saw ahead of him the silvery gleam of a ship's side. Afraid to use his light, he crept toward the bow of the craft, past a huge hole, and reached the name-plate. Following the deeply engraved characters, he slowly spelled out the name "G-L-O-R-," his heart gave a great thump. Gloriana, the Earth-Mars passenger transport into which his own Jean had stepped so happily a year previously!

A sudden hope flared up and then died down as he remembered the gaping hole he had just passed. The cowards had probably attacked without warning; the terrible cold of outer space had flooded through the opening made by that sharp-pointed prow,—. He could not bear to carry the image further; with a sob in his throat and murderous hatred in his heart, he continued his search for the pirate stronghold.

Winding his way among other shattered ships, he came to the base of the towering cliff, and turned to the right along it, finding his way by constantly touching the hard rock with his gloved hand. Suddenly there was a space where he could touch nothing, then the texture of the material changed.

Carefully shielding the glow, he flashed a light on the wall for a moment. It was metal, not rock! The pirates had walled in a cave with plates from the captured transports; probably they were living within, in all the luxury of their stolen wealth.

A few yards farther on his searching hand touched a seam in the metal, still farther, another, evidently the air-lock through which the pirates took their ship into the cave. Holden sat down to think. At that moment the wall against which he leaned began to move slowly outward! A dim ray of light came from the opening, which, as he turned to look, he saw to be an air-lock. The inner door was closed, obviously someone was expected to enter. He drew a deep breath, clasped his gun firmly in his right hand, and plunged in.

As soon as he entered, the outer door closed; he heard valves click open, air rushed into the chamber, and the inner door slowly opened, revealing a long hall, dark and ominous.

Without removing the helmet of his space-suit, he started down the hall, but had gone no more than a few steps before he felt a hand on his sleeve, drawing him through a darkened doorway. The door closed, a light flashed on, and before him stood, smiling and happy, his sweetheart, Jean!

With a single movement he flung off his helmet and seized her in his arms. For a short, delicious moment she clung to him, whispering those words that lovers know so well. At last she said, "We haven't a minute to lose, Jack. Let me tell you all I know about this place."

"But Jean, how did you get here? How does it happen that you had access to the air-lock?"

"I was captured by these fiends, and am a prisoner, together with about fifteen others, only five of them being men. All the rest were killed, either when the pirates rammed the ships, or here, when they decided the place was becoming crowded." Her face paled at the memory of the horrible massacres, but she went bravely on.

"We have no space-suits, and the pirates, of whom there are perhaps seventy-five, let us wander around pretty much as we please. We know of practically everything that goes on. I happened to hear your name mentioned in the phone room the other day, when a spy on your ship sent a message. When the pirates brought their ship in, crippled by the fight, I was sure that you were around somewhere. I have been watching ever since, making use of a sound detector pieced together from some scraps of material I picked up unnoticed.

"There aren't any guards because the gang is busy repairing the Silver Death, as they call their ship, preparatory to finishing the job they started today. Oh, Jack, you must go, now. They may be through at any time. I don't know when I will see you again, if ever, but I couldn't resist talking to you, touching you, just once more."

"One moment, dear. I have an idea. Is there any compartment, farther back or lower down, where you could gather the prisoners together, and be safe in case the outer wall was broken down?"

"Yes," she replied breathlessly, "one of the older, smaller caves is still airtight, and while the gang is busy on the Silver Death we could go there and close the locks. What good would that do, though? They are certain you can't get in here, or they wouldn't leave the place unguarded. They have your ship surrounded by a wave-proof shield, so you can't communicate with the others of your fleet, you know."

"I know that, but I think I can steal a leaf from their own book. Will they all be working, say three hours from now?"

"I think so. Your guns did a great deal of damage, weakening the forward structures of their craft."

"All right. Get your friends together in the old cave you mentioned, seal it, and then wait till I come back."

Tenderly he kissed her good-bye, then hastened away, anxious to get his work done before the shadow of the cliff again receded.

Thanking the fates for the good fortune that had saved Jean, and had led her to the air-lock at the moment he was there, he stumbled over the rocks and dust piles until halted by the picket line surrounding the San Francisco. He called the men into the ship, and hastened to the pilot room, where Edwards was testing the controls.

"Any luck?"

"Yes, a lot. Can you get the ship in shape to travel in three hours?"

"She's in pretty good shape now, although not capable of the trip back to Earth."

Captain Linet entered at that moment, and with him Professor Erickson.

Holden recounted his adventures of the last hour and then set forth his plan.

"The cave is walled up with thin plating from the ships the pirates have brought in here. The entire gang is at work, repairing their own flier; none of them, or at least only a few, are wearing space suits. I propose to drive the bow of the San Francisco into the wall of their cave, previously weakening it by a few bursts from the hexoxen guns!"

"It is possible," replied Edwards, "but it will probably put us out of commission altogether."

"In any case," put in Erickson, "we will be rid of this damnable shield, and can communicate with our companions."

It certainly was the only plan, for, as soon as the pirates had repaired their ship, another unequal battle would be waged, with the result very little in doubt.

All hands set to work completing repairs on the main stern tubes, the only ones necessary to drive the San Francisco forward. In less than three hours, Edwards pronounced the work done to his satisfaction.

As the light began to creep in toward the base of the cliff, the huge ship rose slightly off the ground, the tubes glowed red and, guided by a powerful searchlight installed on the bow, Edwards pointed his craft toward the gleaming metal patch that marked the position of the pirate cave.

At short range, Holden, Linet, and Erickson opened with the three hexoxen guns. They saw the bursts take effect on the metal. Edwards turned the power on full, and they felt the floor leaping under them. Would the bow of the San Francisco hold? Would they all be crushed to death at the impact? Another moment would tell. Holden saw the metal plates dead ahead, could distinguish the seams marking the air-lock.

He fired one final shot, and flung himself to the floor of the pilot room, endeavoring to find some means of bracing himself for the shock. Then it came! Torn from his position, he saw the plates buckling and heaving about him. The lights went out. A great crash sounded in his ears, and everything went black. In a moment he regained consciousness, and staggered to his feet, bruised and dizzy. Thank God, his space suit had not been harmed! A faint glow from the outside made things visible and he saw that the shock had torn a huge piece out of the plating of the pilot room.

A hand clutched his elbow, and through the phone in his space suit he heard Linet's voice.

"Erickson and Edwards are knocked out. Let's see what we did to these chaps here."

Rushing back through the corridor, they collected as many of the crew as were able to move, flung open the heavy doors of the air-lock, and scrambled down to the floor of the cave.

Here and there lay bodies, pirates caught unawares. Suddenly Holden saw a blue flash. One of the mechanics clutched at his breast and fell, dead in an instant.

"Some of these fellows are still alive. They're using ray pistols," Holden shouted into his suit phone.

Even as he spoke he heard the sound of running feet from the darkness in the rear of the cave, where the bow of the Silver Death was barely visible in her cradle, and in a moment at least fifty figures, pirates who had somehow escaped the fatal cold of space, clad in clumsy suits and brandishing pistols, flung themselves desperately upon the smaller party.

Blue flashes were everywhere as the battle commenced, but the only sound was of struggling feet, with an occasional thud as a body hit the floor. The pirates had been weakened by their long stay on the moon, and moved slowly, but the surprise of their attack, and the superiority of numbers had given them some advantage. It was man to man fighting, savage and merciless.

Holden, with a neat dive, knocked the feet from under a huge fellow who had trained a pistol on him, and they rolled over and over, each trying desperately to gain a second's advantage. He heard a dull crash to one side, as Captain Linet, jumping high into the air, landed with stunning force on a bewildered assailant. Thinking of Jean, waiting for him in some dim corner of the cave, he redoubled his efforts.

For a fraction of a second his pistol pointed toward his antagonist's body, and that was enough. He pressed the release, and the deadly ray shot into the body beneath him, dealing instant death. Freeing himself from the cold grip, he ducked an empty pistol flung at him by a new assailant. Again his finger bent, and another body dropped to join those lying motionless on the floor.

A fast-moving shadow caught his eye. He saw one of the pirates detach himself from a writhing group and head for the side of the cave. That was the place where Jean had said she would be waiting!

Pausing only an instant to make sure that his pistol was still charged, Holden sprang in pursuit of the fleeing form. He saw him stoop and pick up a heavy bar from the floor. The coward was going to burst open the chamber where the helpless captives waited! It was impossible to aim at that speed, so Holden forced his flying feet to move still faster, and foot by foot he drew closer to the man he pursued. Metal plates again gleamed in front of him, and he saw the pirate raise the bar high over his head, preparing for a blow which would crush the thin plates. The tiniest hole would mean death to the captives, who had no means of protecting themselves.

With one last desperate effort, Holden jumped, his Earth-trained muscles carrying him high into the air, while his pistol stabbed the partial darkness with vivid rays. Dodging and ducking, the pirate evaded the fatal stabs, while his bar beat a loud tattoo against the metal. Holden struck at him with his now useless pistol as he landed. The blow missed, and, losing his balance, he staggered and fell, past his foe, who quickly turned, raising his bar for a coup de grace which never landed. The familiar flash of a pistol once more illuminated the scene, the bar dropped from dead hands, and Holden scrambled to his feet.

A voice was speaking through his suit phone, and he recognized it as Erickson's. "I just came to, tumbled out of that hole in the pilot room, saw the flash of your pistol, and here I am."

The old professor appeared, wobbling slightly, but still game. The flashes toward the mouth of the cave had grown fewer. Leaving Erickson to guard the compartment of the captives, Holden hurried back to the fight. Even as he went, the flashes died out altogether, and he heard Linet's hearty voice in the phone. "Holden, where are you? We've cleaned out them all down here."

Light was now flooding in from outside, and bodies could be seen lying thick on the floor, cold and stiff in death. Sadly Holden recognized many of them as his own men. After a hasty conference with Linet, he gathered together fifteen space suits, and with an escort helping to carry them, he hurried back to Jean.

The door of the air-lock opened as his party approached. They went in, heard the swish of air entering, and in a few minutes the inner door swung wide. A happy crowd of men and women surrounded them, as they rid themselves of their helmets. Holden felt Jean's arms around him, her sweet lips once more on his. For a second they clung together, then parted, for there was work to be done. The space suits were distributed and, as he led the way back to the San Francisco, Jean told him briefly the details of the long year of imprisonment.

"They gave us warning before they rammed us, as they wanted to save the women, for a purpose you can guess. Fortunately, there were never enough of us to go around, and these men, exiles from two planets, were always quarreling among themselves, so we were quite safe. We just existed, praying that some exploring expedition would find us, or that the Silver Death would meet a ship too strong for her to ram and, fleeing here for refuge, be trailed."

Holden sighted Captain Linet hurrying toward them. In the light now flooding the entire cavern, he could see lines of despair and hopelessness written over the florid face.

"What's the matter?"

"Matter enough," came the ominous answer. "The space phone on our ship is entirely disabled. We won't be able to get in touch with the Ganymede or the Los Angeles. In a few days, the hexoxen charges they plant will commence to go off, and that will be the end of us."

Holden stopped, stunned by the news. Fleeting visions of happiness with Jean vanished into thin air. He would be destroyed by the chemical he had invented, with which he had hoped to save the world.

"I thought we might get out in the Silver Death," continued the captain, "but the entrance is entirely blocked by our own ship, and I'm afraid it will never move again."

Then Jean's clear voice cut in. "How about the space phone on the Silver Death? Won't it work?"

"Why, of course it will," laughed the captain, amused at his own stupidity.

Stumbling and tripping in their haste, the three hurried through the open air lock of the pirate craft, into the pilot room.

Holden feverishly set to work, whirling the strange dials, pushing this button, then that. At last a faint roar sounded in the loud speaker. Pressing his helmet against the transmitter, so that the vibrations would carry his voice, he shouted, "Ganymede, Los Angeles, Holden calling."

"What ho?" came a cheery voice, which he recognized as belonging to Huges, commander of the Los Angeles.

Breathing a sigh of relief, he explained the situation. Busy days followed. Hexoxen and Europium from the San Francisco were transferred to the other ships, with as much of the treasure collected by the pirates as could be loaded into the cramped quarters.

With Huges and Rogers assisting, Holden revised the schedule for planting the charges.

"We simply haven't time," he explained, "to set the charges as close together as I had planned. There's nothing to do but get all of them in that we can, and then hope that conditions in the interior of the moon will be of a nature to promote the action of the hexoxen."

The ships' crews understood only too well the importance and danger of their work, and during the days that followed they toiled like a gang of madmen. Parties raced each other over the rough surface of the dead satellite, grimly determined that their efforts to save the world should not be in vain. Even the men of the party which had been rescued, weakened as they were by their long stay in the pirate cave, insisted on giving what help they could.

Finally came the day when the first charges were set to go off. Holden sat in the pilot room of the Ganymede, his eyes on the chronometer, while Captain Linet swept the desolate plain with powerful binoculars for the cloud of dust which would signal the return of the last party.

"Five minutes yet, Captain," Holden said in a low voice. "Tell the Los Angeles to pull out. The first charges are scarcely two hundred miles from here, and I'm not certain how fast the reaction will travel."

Five minutes. Two minutes. The silver shape of the Los Angeles was already fading in the distance. Suddenly a sharp shock rocked the stony bed on which the Ganymede was resting. Simultaneously five figures appeared, racing at full speed for the ship. Shock after shock tore at the ground beneath their feet. Holden stood at the controls, waiting for the signal that his five comrades were safely aboard. To his tensed nerves it seemed hours before the welcome sound came to his ears, and with a sigh of relief he opened the power into the stern tubes, and laughed happily as the huge ship shot away from the heaving surface of the dying moon.

Anxious seconds passed. From the height to which they had risen, a great part of the moon was visible, and for the first time Holden realized the full power of the chemical which his ingenuity had devised. Immense tongues of flame ripped through the dust and rock of the satellite, sending dense clouds of vapor bellowing out into space. Mighty mountains disappeared in an instant.

The Ganymede was traveling at full speed, and yet it seemed as though at any moment the conflagration might reach out, consuming the space ship in that all-engulfing reaction. Holden manipulated the controls with flying fingers, seeking to get every available bit of speed from the metal monster which was carrying its precious cargo of human beings away from a terrible death.

Far ahead he could see the shape of the Los Angeles, now safely outside the danger zone. Thin clouds of vapor floated around the Ganymede, then suddenly cleared.

Captain Linet gave a shout of joy as he read the distance recorded on the dials. "Jack, my boy, we're safe. We're outside the limit to which the reaction can extend."

With the three ships playing their deadly beams on the moon, Holden watched the immense craters, the towering mountains, and the desolate plains of the moon slowly vaporize.

It was an awe-inspiring sight, as this dead world slowly melted into the nothingness of space, as though a disease of matter were wasting it inexorably away.

No doubt, on the earth, as the contours of the moon slowly blurred and became indistinct, with the accumulation of vapor around its now ragged rim, there must have been terror and consternation. And as the moon slowly evaporated in the skies a virtual panic must have ensued among the Earth's people.

The hand of a terrible fate, or the coming of the end of the world, must have been shouted from city to city as the only explanation of this apparent disaster in the heavens.

But the work had to go on....

For days, the Ganymede and the Los Angeles cruised through the thin clouds, spreading between them the anti-gravitational shield, while the sections of vapor, freed of their mutual attraction, drifted out into uncharted space.

It was slow, dangerous work, cutting those sections off from the main mass, and maintaining the proper position until they had floated off into space. Occasional particles of rock, small but deadly, clattered against the hard shell of the space ship. Fortunately, no fragments of appreciable size were encountered; the hexoxen had done its work thoroughly. For eight days the powerful ray sliced and repelled. Under its influence huge clouds of vapor, the ghostly remains of the calm globe which had innocently threatened the earth, hurtled off into the farthest reaches of space, there to sink at last into the substance of some flaming star.

At last the work was finished, and the two ships, saviors of the Earth, turned their bows toward home to carry to the awestruck people of Earth the glad news that interplanetary commerce would be as free of pirates thereafter as the Earth would be free of the disastrous quakes.

And Jack Holden, at last, faced with a light heart the honors that would be his, knowing that he could now share them with the girl of his dreams.

THE END.