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