n the day of the next full moon every living thing on earth will be wiped out of existence—unless you succeed in your mission, Lee."

Nathaniel Lee looked into the face of Silas Stark, President of the United States of the World, and nodded grimly. "I'll do my best, Sir," he answered.

"You have the facts. We know who this self-styled Black Caesar is, who has declared war upon humanity. He is a Dane named Axelson, whose father, condemned to life imprisonment for resisting the new world-order, succeeded in obtaining possession of an interplanetary liner.

"He filled it with the gang of desperate men who had been associated with him in his successful escape from the penitentiary. Together they sailed into Space. They disappeared. It was supposed that they had somehow met their death in the ether, beyond the range of human ken.

"Thirty years passed, and then this son of Axelson, born, according to his own story, of a woman whom the father had persuaded to accompany him into Space, began to radio us. We thought at first it was some practical joker who was cutting in.

"When our electricians demonstrated beyond doubt that the voice came from outer space, it was supposed that some one in our Moon Colony had acquired a transmitting machine. Then the ships we sent to the Moon Colony for gold failed to return. As you know, for seven weeks there has been no communication with the Moon. And at the last full moon the—blow—fell.

"The world depends upon you, Lee. The invisible rays that destroyed every living thing from China to Australia—one-fifth of the human race—will fall upon the eastern seaboard of America when the moon is full again. That has been the gist of Axelson's repeated communications.

"We shall look to you to return, either with the arch-enemy of the human race as your prisoner, or with the good news that mankind has been set free from the menace that overhangs it.

"God bless you, my boy!" The President of the United States of the World gripped Nat's hand and stepped down the ladder that led from the landing-stage of the great interplanetary space-ship.

he immense landing-field reserved for the ships of the Interplanetary Line was situated a thousand feet above the heart of New York City, in Westchester County. It was a flat space set on the top of five great towers, strewn with electrified sand, whose glow had the property of dispersing the sea fogs. There, at rest upon what resembled nothing so much as iron claws, the long gray shape of the vacuum flyer bulked.

Nat sneezed as he watched the operations of his men, for the common cold, or coryza, seemed likely to be the last of the germ diseases that would yield to medical science, and he had caught a bad one in the Capitol, while listening to the debate in the Senate upon the threat to humanity. And it was cold on the landing-stage, in contrast to the perpetual summer of the glass-roofed city below.

But Nat forgot the cold as he watched the preparations for the ship's departure. Neon and nitrogen gas were being pumped under pressure into the outer shell, where a minute charge of leucon, the newly discovered element that helped to counteract gravitation, combined with them to provide the power that would lift the vessel above the regions of the stratosphere.

In the low roof-buildings that surrounded the stage was a scene of tremendous activity. The selenium discs were flashing signals, and the radio receivers were shouting the late news; on the great power boards dials and light signals stood out in the glow of the amylite tubes. On a rotary stage a thousand feet above the ship a giant searchlight, visible for a thousand miles, moved its shaft of dazzling luminosity across the heavens.

Now the spar-aluminite outer skin of the ship grew bright with the red neon glare. Another ship, from China, dropped slowly to its stage near by, and the unloaders swarmed about the pneumatic tubes to receive the mail. The teleradio was shouting news of a failure of the Manchurian wheat crop. Nat's chief officer, a short cockney named Brent, came up to him.

"Ready to start, Sir," he said.

at turned to him. "Your orders are clear?"

"Yes, Sir."

"Send Benson here."

"I'm here, Sir." Benson, the ray-gunner in charge of the battery that comprised the vessel's armament, a lean Yankee from Connecticut, stepped forward.

"You know your orders, Benson? Axelson has seized the Moon and the gold-mines there. He's planning to obliterate the Earth. We've got to go in like mad dogs and shoot to kill. No matter if we kill every living thing there, even our own people who are inmates of the Moon's penal settlement, we've got to account for Axelson."

"Yes, Sir."

"We can't guess how he got those gold-ships that returned with neon and argon for the Moon colonists. But he mustn't get us. Let the men understand that. That's all."

"Very good, Sir."

The teleradio suddenly began to splutter: A-A-A, it called. And instantly every sound ceased about the landing-stage. For that was the call of Axelson, somewhere upon the Moon.

"Axelson speaking. At the next full moon all the American Province of the World Federation will be annihilated, as the Chinese Province was at the last. There's no hope for you, good people. Send out your vacuum liners. I can use a few more of them. Within six months your world will be depopulated, unless you flash me the signal of surrender."

Would the proud old Earth have to come to that? Daily those ominous threats had been repeated, until popular fears had become frenzy. And Nat was being sent out as a last hope. If he failed, there would be nothing but surrender to this man, armed with a super-force that enabled him to lay waste the Earth from the Moon.

Within one hour, those invisible, death-dealing rays had destroyed everything that inhaled oxygen and exhaled carbon. The ray with which the liner was equipped was a mere toy in comparison. It would kill at no more than 500 miles, and its action was quite different.

As a prelude to Earth's surrender, Axelson demanded that World President Stark and a score of other dignitaries should depart for the Moon as hostages. Every ray fortress in the world was to be dismantled, every treasury was to send its gold to be piled up in a great pyramid on the New York landing-stage. The Earth was to acknowledge Axelson as its supreme master.

he iron claws were turning with a screwlike motion, extending themselves, and slowly raising the interplanetary vessel until she looked like a great metal fish with metal legs ending with suckerlike disks. But already she was floating free as the softly purring engines held her in equipoise. Nat climbed the short ladder that led to her deck. Brent came up to him again.

"That teleradio message from Axelson—" he began.

"Yes?" Nat snapped out.

"I don't believe it came from the Moon at all."

"You don't? You think it's somebody playing a hoax on Earth? You think that wiping out of China was just an Earth-joke?"

"No, Sir." Brent stood steady under his superior's sarcasm. "But I was chief teleradio operator at Greenwich before being promoted to the Province of America. And what they don't know at Greenwich they don't know anywhere."

Brent spoke with that self-assurance of the born cockney that even the centuries had failed to remove, though they had removed the cockney accent.

"Well, Brent?"

"I was with the chief electrician in the receiving station when Axelson was radioing last week. And I noticed that the waves of sound were under a slight Doppler effect. With the immense magnification necessary for transmitting from the Moon, such deflection might be construed as a mere fan-like extension. But there was ten times the magnification one would expect from the Moon; and I calculated that those sound-waves were shifted somewhere."

"Then what's your theory, Brent?"

"Those sounds come from another planet. Somewhere on the Moon there's an intercepting and re-transmitting plant. Axelson is deflecting his rays to give the impression that he's on the Moon, and to lure our ships there."

"What do you advise?" asked Nat.

"I don't know, Sir."

"Neither do I. Set your course Moonward, and tell Mr. Benson to keep his eyes peeled."

he Moon Colony, discovered in 1976, when Kramer, of Baltimore, first proved the practicability of mixing neon with the inert new gas, leucon, and so conquering gravitation, had proved to be just what it had been suspected of being—a desiccated, airless desolation. Nevertheless, within the depths of the craters a certain amount of the Moon's ancient atmosphere still lingered, sufficient to sustain life for the queer troglodytes, with enormous lung-boxes, who survived there, browsing like beasts upon the stunted, aloe-like vegetation.

Half man, half ape, and very much unlike either, these vestiges of a species on a ruined globe had proved tractable and amenable to discipline. They had become the laborers of the convict settlement that had sprung up on the Moon.

Thither all those who had opposed the establishment of the World Federation, together with all persons convicted for the fourth time of a felony, had been transported, to superintend the efforts of these dumb, unhuman Moon dwellers. For it had been discovered that the Moon craters were extraordinarily rich in gold, and gold was still the medium of exchange on Earth.

To supplement the vestigial atmosphere, huge stations had been set up, which extracted the oxygen from the subterranean waters five miles below the Moon's crust, and recombined it with the nitrogen with which the surface layer was impregnated, thus creating an atmosphere which was pumped to the workers.

Then a curious discovery had been made. It was impossible for human beings to exist without the addition of those elements existing in the air in minute quantities—neon, krypton, and argon. And the ships that brought the gold bars back from the Moon had conveyed these gaseous elements there.

he droning of the sixteen atomic motors grew louder, and mingled with the hum of gyroscopes. The ladder was drawn up and the port hole sealed. On the enclosed bridge Nat threw the switch of durobronze that released the non-conducting shutter which gave play to the sixteen great magnets. Swiftly the great ship shot forward into the air. The droning of the motors became a shrill whine, and then, growing too shrill for human ears to follow it, gave place to silence.

Nat set the speed lever to five hundred miles an hour, the utmost that had been found possible in passing through the earth's atmosphere, owing to the resistance, which tended to heat the vessel and damage the delicate atomic engines. As soon as the ether was reached, the speed would be increased to ten or twelve thousand. That meant a twenty-two hour run to the Moon Colony—about the time usually taken.

He pressed a lever, which set bells ringing in all parts of the ship. By means of a complicated mechanism, the air was exhausted from each compartment in turn, and then replaced, and as the bells rang, the men at work trooped out of these compartments consecutively. This had been originated for the purpose of destroying any life dangerous to man that might unwittingly have been imported from the Moon, but on one occasion it had resulted in the discovery of a stowaway.

Then Nat descended the bridge to the upper deck. Here, on a platform, were the two batteries of three ray-guns apiece, mounted on swivels, and firing in any direction on the port and starboard sides respectively. The guns were enclosed in a thin sheath of osmium, through which the lethal rays penetrated unchanged; about them, thick shields of lead protected the gunners.

He talked with Benson for a while. "Don't let Axelson get the jump on you," he said. "Be on the alert every moment." The gunners, keen-looking men, graduates from the Annapolis gunnery school, grinned and nodded. They were proud of their trade and its traditions; Nat felt that the vessel was safe in their hands.

The chief mate appeared at the head of the companion, accompanied by a girl. "Stowaway, Sir," he reported laconically. "She tumbled out of the repair shop annex when we let out the air!"

at stared at her in consternation, and the girl stared back at him. She was a very pretty girl, hardly more than twenty-two or three, attired in a businesslike costume consisting of a leather jacket, knickers, and the black spiral puttees that had come into style in the past decade. She came forward unabashed.

"Well, who are you?" snapped Nat.

"Madge Dawes, of the Universal News Syndicate," she answered, laughing.

"The devil!" muttered Nat. "You people think you run the World Federation since you got President Stark elected."

"We certainly do," replied the girl, still laughing.

"Well, you don't run this ship," said Nat. "How would you like a long parachute drop back to Earth?"

"Don't be foolish, my dear man," said Madge. "Don't you know you'll get wrinkles if you scowl like that? Smile! Ah, that's better. Now, honestly, Cap we just had to get the jump on everybody else in interviewing Axelson. It means such a lot to me."

Pouts succeeded smiles. "You're not going to be cross about it, are you?" she pleaded.

"Do you realize the risk you're running, young woman?" Nat demanded. "Are you aware that our chances of ever getting back to Earth are smaller than you ought to have dreamed of taking?"

"Oh, that's all right," the girl responded. "And now that we're friends again, would you mind asking the steward to get me something to eat? I've been cooped up in that room downstairs for fifteen hours, and I'm simply starving."

Nat shrugged his shoulders hopelessly. He turned to the chief mate. "Take Miss Dawes down to the saloon and see that Wang Ling supplies her with a good meal," he ordered. "And put her in the Admiral's cabin. That good enough for you?" he asked satirically.

"Oh that'll be fine," answered the girl enthusiastically. "And I shall rely on you to keep me posted about everything that's going on. And a little later I'm going to take X-ray photographs of you and all these men." She smiled at the grinning gunners. "That's the new fad, you know, and we're going to offer prizes for the best developed skeletons in the American Province, and pick a King and Queen of Beauty!"

radio, Sir!"

Nat, who had snatched a brief interval of sleep, started up as the man on duty handed him the message. The vessel had been constantly in communication with Earth during her voyage, now nearing completion, but the dreaded A-A-A that prefaced this message told Nat that it came from Axelson.

"Congratulations on your attempt," the message ran, "I have watched your career with the greatest interest, Lee, through the medium of such scraps of information as I have been able to pick up on the Moon. When you are my guest to-morrow I shall hope to be able to offer you a high post in the new World Government that I am planning to establish. I need good men. Fraternally, the Black Caesar."

Nat whirled about. Madge Dawes was standing behind him, trying to read the message over his shoulder.

"Spying, eh?" said Nat bitterly.

"My dear man, isn't that my business?"

"Well, read this, then," said Nat, handing her the message. "You're likely to repent this crazy trick of yours before we get much farther."

And he pointed to the cosmic-ray skiagraph of the Moon on the curved glass dome overhead. They were approaching the satellite rapidly. It filled the whole dome, the craters great black hollows, the mountains standing out clearly. Beneath the dome were the radium apparatus that emitted the rays by which the satellite was photographed cinematographically, and the gyroscope steering apparatus by which the ship's course was directed.

Suddenly a buzzer sounded a warning. Nat sprang to the tube.

"Gravitational interference X40, gyroscopic aberrancy one minute 29," he called. "Discharge static electricity from hull. Mr. Benson, stand by."

"What does that mean?" asked Madge.

"It means I shall be obliged if you'll abstain from speaking to the man at the controls," snapped Nat.

"And what's that?" cried Madge in a shriller voice, pointing upward.

cross the patterned surface of the Moon, shown on the skiagraph, a black, cigar-shaped form was passing. It looked like one of the old-fashioned dirigibles, and the speed with which it moved was evident from the fact that it was perceptibly traversing the Moon's surface. Perhaps it was travelling at the rate of fifty thousand miles an hour.

Brent, the chief officer, burst up the companion. His face was livid.

"Black ship approaching us from the Moon, Sir," he stammered. "Benson's training his guns, but it must be twenty thousands miles away."

"Yes, even our ray-guns won't shoot that distance," answered Nat. "Tell Benson to keep his guns trained as well as he can, and open fire at five hundred."

Brent disappeared. Madge and Nat were alone on the bridge. Nat was shouting incomprehensible orders down the tube. He stopped and looked up. The shadow of the approaching ship had crossed the Moon's disk and disappeared.

"Well, young lady, I think your goose is cooked," said Nat. "If I'm not mistaken, that ship is Axelson's, and he's on his way to knock us galley-west. And now oblige me by leaving the bridge."

"I think he's a perfectly delightful character, to judge from that message he sent you," answered Madge, "and—"

Brent appeared again. "Triangulation shows ten thousand miles, Sir," he informed Nat.

"Take control," said Nat. "Keep on the gyroscopic course, allowing for aberrancy, and make for the Crater of Pytho. I'll take command of the guns." He hurried down the companion, with Madge at his heels.

he gunners stood by the ray-guns, three at each. Benson perched on a revolving stool above the batteries. He was watching a periscopic instrument that connected with the bridge dome by means of a tube, a flat mirror in front of him showing all points of the compass. At one edge the shadow of the black ship was creeping slowly forward.

"Eight thousand miles, Sir," he told Nat. "One thousand is our extreme range. And it looks as if she's making for our blind spot overhead."

Nat stepped to the speaking-tube. "Try to ram her," he called up to Brent. "We'll open with all guns, pointing forward."

"Very good, Sir," the Cockney called back.

The black shadow was now nearly in the centre of the mirror. It moved upward, vanished. Suddenly the atomic motors began wheezing again. The wheeze became a whine, a drone.

"We've dropped to two thousand miles an hour, Sir," called Brent.

Nat leaped for the companion. As he reached the top he could hear the teleradio apparatus in the wireless room overhead begin to chatter:

"A-A-A. Don't try to interfere. Am taking you to the Crater of Pytho. Shall renew my offer there. Any resistance will be fatal. Axelson."

And suddenly the droning of the motors became a whine again, then silence. Nat stared at the instrument-board and uttered a cry.

"What's the matter?" demanded Madge.

Nat swung upon her. "The matter?" he bawled. "He's neutralized our engines by some infernal means of his own, and he's towing us to the Moon!"

he huge sphere of the Moon had long since covered the entire dome. The huge Crater of Pytho now filled it, a black hollow fifty miles across, into which they were gradually settling. And, as they settled, the pale Earth light, white as that of the Moon on Earth, showed the gaunt masses of bare rock, on which nothing grew, and the long stalactites of glassy lava that hung from them.

Then out of the depths beneath emerged the shadowy shape of the landing-stage.

"You are about to land," chattered the radio. "Don't try any tricks; they will be useless. Above all, don't try to use your puny ray. You are helpless."

The ship was almost stationary. Little figures could be seen swarming upon the landing-stage, ready to adjust the iron claws to clamp the hull. With a gesture of helplessness, Nat left the bridge and went down to the main deck where, in obedience to his orders, the crew had all assembled.

"Men, I'm putting it up to you," he said. "Axelson, the Black Caesar, advises us not to attempt to use the Ray-guns. I won't order you to. I'll leave the decision with you."

"We tried it fifteen minutes ago, Sir," answered Benson. "I told Larrigan to fire off the stern starboard gun to see if it was in working order, and it wasn't!"

At that moment the vessel settled with a slight jar into the clamps. Once more the teleradio began to scream:

"Open the port hold and file out slowly. Resistance is useless. I should turn my ray upon you and obliterate you immediately. Assemble on the landing-stage and wait for me!"

"You'd best obey," Nat told his men. "We've got a passenger to consider." He glared at Madge as he spoke, and Madge's smile was a little more tremulous than it had been before.

"This is the most thrilling experience of my life, Captain Lee," she said. "And I'll never rest until I've got an X-Ray photograph of Mr. Axelson's skeleton for the Universal News Syndicate."

ne by one, Nat last, the crew filed down the ladder onto the landing-stage, gasping and choking in the rarefied air that lay like a blanket at the bottom of the crater. And the reason for this was only too apparent to Nat as soon as he was on the level stage.

Overhead, at an altitude of about a mile, the black ship hung, and from its bow a stupendous searchlight played to and fro over the bottom of the crater, making it as light as day. And where had been the mining machinery, the great buildings that had housed convicts and Moon people, and the huge edifice that contained the pumping station, there was—nothing.

The devilish ray of Axelson had not merely destroyed them, it had obliterated all traces of them, and the crew of the liner were breathing the remnants of the atmosphere that still lay at the bottom of the Crater of Pytho.

But beside the twin landing-stages, constructed by the World Federation, another building arose, with an open front. And that front was a huge mirror, now scintillating under the searchlight from the black ship.

"That's it, Sir!" shouted Brent.

"That's what?" snapped Nat.

"The deflecting mirror I was speaking of. That's what deflected the ray that wiped out China. The ray didn't come from the Moon. And that's the mirror that deflects the teleradio waves, the super-Hertzian rays that carry the sound."

Nat did not answer. Sick at heart at the failure of his mission, he was watching the swarm of Moon men who were at work upon the landing-stage, turning the steel clamps and regulating the mechanism that controlled the apparatus. Dwarfed, apish creature, with tiny limbs, and chests that stood out like barrels, they bustled about, chattering in shrill voices that seemed like the piping of birds.

It was evident that Axelson, though he had wiped out the Moon convicts and the Moon people in the crater, had reserved a number of the latter for personal use.

he black ship was dropping into its position at the second landing-stage, connected with the first by a short bridge. The starboard hold swung open, and a file of shrouded and hooded forms appeared, masked men, breathing in condensed air from receptacles upon their chests, and staring with goggle eyes at their captives. Each one held in his hand a lethal tube containing the ray, and, as if by command, they took up their stations about their prisoners.

Then, at a signal from their leader, they suddenly doffed their masks.

Nat looked at them in astonishment. He had not known whether these would be Earth denizens or inhabitants of some other planet. But they were Earth men. And they were old.

Men of sixty or seventy, years, with long, gray beards and wrinkled faces, and eyes that stared out from beneath penthouses of shaggy eyebrows. Faces on which were imprinted despair and hopelessness.

Then the first man took off his mask and Nat saw a man of different character.

A man in the prime of life, with a mass of jet black hair and a black beard that swept to his waist, a nose like a hawk's, and a pair of dark blue eyes that fixed themselves on Nat's with a look of Luciferian pride.

"Welcome, Nathaniel Lee," said the man, in deep tones that had a curious accent which Nat could not place. "I ought to know your name, since your teleradios on Earth have been shouting it for three days past as that of the man who is to save Earth from the threat of destruction. And you know me!"

"Axelson—the Black Caesar," Nat muttered. For the moment he was taken aback. He had anticipated any sort of person except this man, who stood, looked, and spoke like a Viking, this incarnation of pride and strength.

Axelson smiled—and then his eyes lit upon Madge Dawes. And for a moment he stood as if petrified into a block of massive granite.

"What—who is this?" he growled.

"Why, I'm Madge Dawes, of the Universal News Syndicate," answered the girl, smiling at Axelson in her irrepressible manner. "And I'm sure you're not nearly such a bold, bad pirate as people think, and you're going to let us all go free."

nstantly Axelson seemed to become transformed into a maniac. He turned to the old men and shouted in some incomprehensible language. Nat and Madge, Brent and Benson, and two others who wore the uniforms of officers were seized and dragged across the bridge to the landing-stage where the black ship was moored. The rest of the crew were ordered into a double line.

And then the slaughter began.

Before Nat could even struggle to break away from the gibbering Moon men to whom he and the other prisoners had been consigned, the aged crew of the Black Caesar had begun their work of almost instantaneous destruction.

Streams of red and purple light shot from the ray-pistols that they carried, and before them the crew of the ether-liner simply withered up and vanished. They became mere masses of human dÉbris piled on the landing-stage, and upon these masses, too, the old men turned their implements, until only a few heaps of charred carbon remained on the landing-stage, impalpable as burned paper, and slowly rising in the low atmospheric pressure until they drifted over the crater.

Nat had cried out in horror at the sight, and tried to tear himself free from the grasp of the Moon dwarfs who held him. So had the rest. Never was struggle so futile. Despite their short arms and legs, the Moon dwarfs held them in an unshakable grip, chattering and squealing as they compressed them against their barrel-like chests until the breath was all but crushed out of their bodies.

"Devil!" cried Nat furiously, as Axelson came up to him. "Why don't you kill us, too?" And he hurled furious taunts and abuse at him, in the hope of goading him into making the same comparatively merciless end of his prisoners.

Axelson looked at him calmly, but made no reply. He looked at Madge again, and his features were convulsed with some emotion that gave him the aspect of a fiend. And then only did Nat realize that it was Madge who was responsible for the Black Caesar's madness.

Axelson spoke again, and the prisoners were hustled up the ladder and on board the black vessel.

he Kommandant-Kommissar will see you!" The door of their prison had opened, letting in a shaft of light, and disclosing one of the graybeards, who stood there, pointing at Nat.

"The—who?" Nat demanded.

"The Kommandant-Kommissar, Comrade Axelson," snarled the graybeard.

Nat knew what that strange jargon meant. He had read books about the political sect known as Socialists who flourished in the Nineteenth and Twentieth Centuries, and, indeed, were even yet not everywhere extinct. And with that a flash of intuition explained the presence of these old men on board.

These were the men who had been imprisoned in their youth, with Axelson's father, and had escaped and made their way into space, and had been supposed dead long since. Somewhere they must have survived.

And here they were, speaking a jargon of past generations, and ignorant that the world had changed, relics of the past, dead as the dead Moon from which the black ship was winging away through the ether.

"Don't go, Captain," pleaded Madge. "Tell him we'll all go together."

Nat shook his head. "Maybe I'll be able to make terms with him," he answered, and stepped out upon the vessel's deck.

The graybeard slammed the door and laughed savagely. "You'll make no terms with the Black Caesar," he said. "This is the reign of the proletariat. The bourgeois must die! So Lenin decreed!"

But he stopped suddenly and passed his hand over his forehead like a man awakening from a dream.

"Surely the proletariat has already triumphed on earth?" he asked. "A long time has passed, and daily we expect the summons to return and establish the new world-order. What year is this? Is it not 2017? It is so hard to reckon on Eros."

"On Eros?" thought Nat. "This is the year 2044," he answered. "You've been dreaming, my friend. We've had our new world-order, and it's not in the least like the one you and your friends anticipated."

"Gott!" screamed the old man. "Gott, you're lying to me, bourgeois! You're lying, I tell you!"

o Eros was their destination! Eros, one of the asteroids, those tiny fragments of a broken planet, lying outside the orbit of Mars. Some of these little worlds, of which more than a thousand are known to exist, are no larger than a gentleman's country estate; some are mere rocks in space. Eros, Nat knew, was distinguished among them from the fact that it had an eccentric orbit, which brought it at times nearer Earth than any other heavenly body except the Moon.

Also that it had only been known for thirty years, and that it was supposed to be a double planet, having a dark companion.

That was in Nat's mind as he ascended the bridge to where Axelson was standing at the controls, with one of the graybeards beside him. The door of his stateroom was open, and suddenly there scuttled out of it one of the most bestial objects Nat had ever seen.

It was a Moon woman, a dwarfish figure, clothed in a shapeless garment of spun cellulose, and in her arms she held a heavy-headed Moon baby, whose huge chest stood up like a pyramid, while the tiny arms and legs hung dangling down.

"Here is the bourgeois, Kommandant," said Nat's captor.

Axelson looked at Nat, eye meeting eye in a slow stare. Then he relinquished the controls to the graybeard beside him, and motioned Nat to precede him into the stateroom.

Nat entered. It was an ordinary room, much like that of the captain of the ether-liner now stranded on the Moon. There were a bunk, chairs, a desk and a radio receiver.

Axelson shut the door. He tried to speak and failed to master his emotion. At last he said:

"I am prepared to offer you terms, Nathaniel Lee, in accordance with my promise."

"I'll make no terms with murderers," replied Nat bitterly.

xelson stood looking at him. His great chest rose and fell. Suddenly he put out one great hand and clapped Nat on the shoulder.

"Wise men," he said, "recognize facts. Within three weeks I shall be the undisputed ruler of Earth. Whether of a desert or of a cowed and submissive subject-population, rests with the Earth men. I have never been on Earth, for I was born on Eros. My mother died at my birth. I have never seen another human woman until to-day."

Nat looked at him, trying to follow what was in Axelson's mind.

"My father fled to Eros, a little planet seventeen miles in diameter, as we have found. He called it a heavenly paradise. It was his intention to found there a colony of those who were in rebellion against the tyrants of Earth.

"His followers journeyed to the Moon and brought back Moon women for wives. But there were no children of these unions. Later there were dissensions and civil war. Three-fourths of the colony died in battle with one another.

"I was a young man. I seized the reins of power. The survivors—these old men—were disillusioned and docile. I made myself absolute. I brought Moon men and women to Eros to serve us as slaves. But in a few years the last of my father's old compatriots will have died, and thus it was I conceived of conquering Earth and having men to obey me. For fifteen years I have been experimenting and constructing apparatus, with which I now have Earth at my mercy.

"But I shall need assistance, intelligent men who will obey me and aid me in my plans. That is why I saved you and the other officers of your ether-lines. If you will join me, you shall have the highest post on Earth under me, Nathaniel Lee, and those others shall be under you."

xelson paused, and, loathing the man though he did, Nat was conscious of a feeling of pity for him that he could not control. He saw his lonely life on Eros, surrounded by those phantom humans of the past, and he understood his longing for Earth rule—he the planetary exile, the sole human being of all the planetary system outside Earth, perhaps, except for his dwindling company of aged men.

"To-day, Nathaniel Lee," Axelson went on, "my life was recast in a new mould when I saw the woman you have brought with you. I did not know before that women were beautiful to look on. I did not dream that creatures such as she existed. She must be mine, Nathaniel Lee.

"But that is immaterial. What is your answer to my offer?"

Nat was trying to think, though passion distorted the mental images as they arose in his brain. To Axelson it was evidently incomprehensible that there would be any objection to his taking Madge. Nat saw that he must temporize for Madge's sake.

"I'll have to consult my companions," he answered.

"Of course," answered Axelson. "That is reasonable. Tell them that unless they agree to join me it will be necessary for them to die. Do Earth men mind death? We hate it on Eros, and the Moon men hate it, too, though they have a queer legend that something in the shape of an invisible man raises from their ashes. My father told me that that superstition existed on Earth in his time, too. Go and talk to your companions, Nathaniel Lee."

The Black Caesar's voice was almost friendly. He clapped Nat on the shoulder again, and called the graybeard to conduct him back to his prison.

"Oh, Captain Lee, I'm so glad you're back!" exclaimed Madge. "We've been afraid for you. Is he such a terrible man, this Black Caesar?"

Nat sneered, then grinned malevolently. "Well, he's not exactly the old-fashioned idea of a Sunday-school teacher," he answered. Of course he could not tell the girl about Axelson's proposal.

he little group of prisoners stood on the upper deck of the black ship and watched the Moon men scurrying about the landing-stage as she hovered to her position.

Axelson's father had not erred when he had called the tiny planet, Eros, a heavenly paradise, for no other term could have described it.

They were in an atmosphere so similar to that of Earth that they could breathe with complete freedom, but there seemed to be a lightness and a vigor in their limbs that indicated that the air was supercharged with oxygen or ozone. The presence of this in large amounts was indicated by the intense blueness of the sky, across which fleecy clouds were drifting.

And in that sky what looked like threescore moons were circling with extraordinary swiftness. From thirty to forty full moons, of all sizes, from that of a sun to that of a brilliant planet, and riding black against the blue.

The sun, hardly smaller than when seen from Earth, shone in the zenith, and Earth and Mars hung in the east and north respectively, each like a blood-red sun.

The moons were some of the thousand other asteroids, weaving their lacy patterns in and out among each other. But, stupendous as the sight was, it was toward the terrestrial scene that the party turned their eyes as the black ship settled.

A sea of sapphire blue lapped sands of silver and broke into soft lines of foam. To the water's edge extended a lawn of brightest green, and behind this an arm of the sea extended into what looked like a tropical forest. Most of the trees were palmlike, but towered to immense heights, their foliage swaying in a gentle breeze. There were apparently no elevations, and yet, so small was the little sphere that the ascending curve gave the illusion of distant heights, while the horizon, instead of seeming to rise, lay apparently perfectly flat, producing an extraordinary feeling of insecurity.

Near the water's edge a palatial mansion, built of hewn logs and of a single story, stood in a garden of brilliant flowers. Nearer, beyond the high landing-stage, were the great shipbuilding works, and near them an immense and slightly concave mirror flashed back the light of the sun.

"The death ray!" whispered Brent to Nat.

Axelson came up to the party as the ship settled down. "Welcome to Eros," he said cordially. "My father told me that in some Earth tongue that name meant 'love'."

ever, perhaps, was so strange a feast held as that with which Axelson entertained his guests that day. Dwarfish Moon men passed viands and a sort of palm wine in the great banquet-room, which singularly resembled one of those early twentieth century interiors shown in museums. Only the presence of a dozen of the aged guards, armed with ray-rods, lent a grimness to the scene.

Madge sat on Axelson's right, and Nat on his left. The girl's lightheartedness had left her; her face grew strained as Axelson's motives—which Nat had not dared disclose to her—disclosed themselves in his manner.

Once, when he laid his finger for a moment against her white throat, she started, and for a moment it seemed as if the gathering storm must break.

For Nat had talked with his men, and all had agreed that they would not turn traitor, though they intended to temporize as long as possible, in the hope of catching the Black Caesar unawares.

Then slowly a somber twilight began to fall, and Axelson rose.

"Let us walk in the gardens during the reign of Erebos," he said.

"Erebos?" asked Nat.

"The black world that overshadows us each sleeping period," answered Axelson.

Nat knew what he meant. The dark companion of Eros revolves around it every six hours; the day of Eros would therefore never be longer than six hours, this without reckoning the revolution of Eros around the sun. But owing to its small size, it was probable that it was bathed in almost perpetual sunshine.

The sweet scent of the flowers, much stronger than of any flowers on earth, filled the air. They walked across the green lawn and entered a jungle path, with bamboos and creeping plants on either side, and huge palmlike trees. Behind them stalked the guards with their ray-rods.

A lake of deepest black disclosed itself. Suddenly Madge uttered a scream and clung to Nat. "Look, look!" she cried. "It's horrible!"

uddenly Nat realized that the lake swarmed with monsters. They were of crocodilian form, but twice the size of the largest crocodile, and sprawled over one another in the shallows beside the margin. As the party drew near, an enormous monster began waddling on its clawed feet toward them.

A mouth half the length of the creature opened, disclosing a purplish tongue and hideous fangs. Madge screamed again.

"Ah, so fear exists on Earth, too?" asked Axelson blandly. "That makes my conquest sure. I suspected it, and yet I was not sure that science had not conquered it. But there is no cause for fear. A magnetic field protects us. See!"

For the waddling monster suddenly stopped short as if brought up sharply by the bars of a cage, and drew back.

Axelson turned and wheezed in the Moon language—if the gibbering of the dwarfs could be called speech—and one of the guards answered him.

"These primitive dwellers on Eros I have preserved," said Axelson, "as a means of discipline. The Moon animals are afraid of them. I keep a supply of those who have transgressed my laws to feed them. See!"

He turned and pointed. Two guards were bringing a gibbering, screeching, struggling Moon man with them. Despite his strength, he seemed incapable of making any resistance, but his whole body quivered, and his hideous face was contorted with agony of terror.

At a distance of some fifty feet they turned aside into a little bypath through the jungle, reappearing close beside the Lake upon a raised platform. And what happened next happened so swiftly that Nat was unable to do anything to prevent it.

The guards disappeared; the Moon man, as if propelled by some invisible force, moved forward jerkily to the lake's edge. Instantly one of the saurians had seized him in its jaws, and another had wrenched half the body away, and the whole fighting, squirming mass vanished in the depths.

And from far away came the screeching chant of the Moon men, as if in invocation to some hideous deity.

And, moving perceptibly, the huge black orb of Eros's dark satellite crept over the sky, completely covering it.

xelson stepped forward to where Nat stood, supporting Madge in his arms. The girl had fainted with horror at the scene.

"Your answer Nathaniel Lee," he said softly. "I know you have been postponing the decision. Now I will take the girl, and you shall give me your answer. Will you and these men join me, or will you die as the Moon man died?" He spoke wheezily, as if he, like Nat, had a cold.

And he put his arm around Madge.

Next moment something happened to him that had never happened in his life before. The Black Caesar went down under a well-directed blow to the jaw.

He leaped to his feet trembling with fury and barked a command. Instantly the old guards had hurled themselves forward. And behind them a horde of Moon men came, ambling.

While the guards covered their prisoners with their ray-rods, two Moon men seized each of them, imprisoning him in their unbreakable grasp.

Axelson pointed upward. "When the reign of Erebos is past," he said, "you become food for the denizens of the lake, unless you have agreed to serve me."

And he raised Madge in his arms, laughing as the girl fought and struggled to resist him.

"Madge!" cried Nat, trying to run toward her.

So furious were his struggles that for a moment he succeeded in throwing off the Moon men's grasp. Then he was caught again, and, fighting desperately, was borne off by the dwarfs through the shadows.

They traversed the border of the lake until a small stone building disclosed itself. Nat and the others were thrust inside into pitch darkness. The door clanged; in vain they hurled themselves against it. It was of wood, but it was as solid as the stone itself, and it did not give an inch for all their struggles.

here is your Kommandant?" The whisper seemed in the stone hut itself. "Your Nathaniel Lee. I must speak to him. I am the guard who brought him to the Black Caesar on board the ship."

"I'm here," said Nat. "Where are you?"

"I am in the house of the ray. I am on guard there. I am speaking into the telephone which runs only to where you are. You can speak anywhere in the hut, and I shall hear you."

"Well, what do you want?" asked Nat.

"You love the Earth woman. I remember, when I was a boy, we used to love. I had forgotten. There was a girl in Stamford.... Tell me, is it true that this is the year 2044 and that the proletariat has not yet triumphed?"

"It's true," said Nat. "Those dreams are finished, We're proud of the World Federation. Tell me about Madge Dawes—the Earth woman. Is she safe?"

"He has taken her to his house. I do not think she is harmed. He is ill. He is closely guarded. There are rumors afoot. I do not know."

"What do you want, then?"

"If the Black Caesar dies will you take me back to Earth again? I long so for the old Earth life. I will be your slave, if only I can set foot on Earth before I die."

"Can you rescue us?" Nat held his breath.

"The Moon men are on guard."

"They have no ray-guns and you have."

"The penalty would be terrible. I should be thrown to the monsters."

"Can you get us each a ray-gun? Will you risk it, to get back to Earth?" asked Nat.

A pause. Then, "My friend, I am coming."

Nat heard Benson hissing in his ear, "If we can surprise them, we can get possession of the black ship and return."

"We must get Madge Dawes."

"And smash the mirror," put in Brent.

After that there was nothing to do but wait.

he door clicked open. An indistinct form stood in the entrance. It was already growing light; the dark satellite that eclipsed Eros was passing.

"Hush! I have brought you ray-rods!" It was the old man with whom Nat had spoken on the boat. Under his arm he held five metallic rods, tipped with luminous glass. He handed one to each of the prisoners. "Do you know how to use them?" he asked.

Nat examined his. "It's an old-style rod that was used on earth fifty years ago," he told his men. "I've seen them in museums. It came into use in the Second World War of 1950 or thereabouts. You slip back the safety catch and press this button, taking aim as one did with the pistol. You fellows have seen pistols?"

"My father had an old one," said the chief mate, Barnes.

"How many times can they be fired without reloading?" Nat asked the old guard.

"Ten times; sometimes more; and they were all freshly loaded yesterday."

"Take us to where Axelson is."

"First you must destroy the guards. I sent the one on duty here away on some pretext. But the others may be here at any moment. Talk lower. Are you going to kill them?"

"We must," said Nat.

The old fellow began to sob. "We were companions together. They seized us and imprisoned us together, the capitalists, years ago. I thought the proletariat would have won, and you say it is all different. I am an old man, and life is sad and strange."

"Listen. Is Axelson in the house?" demanded Nat.

"He is in his secret room. I do not know the way. None of us has ever entered it."

"And Madge?"

"She was with him. I do not know anything more." He sank down, groaning, broken.

at pushed his way past him. It was fast growing light now. A ray of sunshine shot from beneath the edge of the dark sphere overhead, which still filled almost all the heavens. At that moment the hideous face and squat body of one of the Moon men came into view at the end of the path. The creature stopped, gibbering with surprise, and then rushed forward, mewing like a cat.

Nat aimed his ray-rod and pressed the button. The streak of light, not quite aimed, in Nat's excitement, sheared off one side of the Moon man's face.

The creature rocked where it stood, raised its voice in a screech, and rushed forward again, arms flailing. And this time Nat got home. The streak passed right through the body of the monster, which collapsed into a heap of calcined carbon.

But its screech had brought the other dwarfs running to the scene. In a moment the path was blocked by a score of the hideous monsters, which, taking in what was happening, came forward in a yelling bunch.

The ray-rods streaked their message of death into the thick of them. Yet so fierce was the rush that some parts got home. Arms, legs, and barrel chests, halves of men, covering the five with that impalpable black powder into which their bodies were dissolving. Nat remembered afterward the horror of a grinning face, apparently loose in the air, and a flailing arm that lashed his chest.

For fifteen seconds, perhaps, it was like struggling with some vampire creatures in a hideous dream. And then, just when it seemed to Nat that he was going mad, he found the path free, and the huddled remnants of the Moon men piled up about him on every side.

He emptied two more ray-shots into the writhing mass, and saw it cease to quiver and then dissolve into the black powder. He turned and looked at his companions. They, too, showed the horror of the strain they had undergone.

"We must kill the guards now," Nat panted. "And then find Madge and save her."

"We're with you," answered Brent, and together the five rushed into the sunlight and the open.

here were no guards on duty at the entrance of the house, and the door stood wide open. Nat rushed through the door at the head of his men. A single guard was in the hall, but he only looked up as they came in. And it was evident that he was in no condition to resist, for he was in the grip of some terrible disease.

His features were swollen so that they were hardly recognizable, and hoarse, panting breaths came from his lungs. He was so far gone that he hardly registered surprise at the advent of the five.

"Where's Axelson?" demanded Nat.

The guard pointed toward the end of the corridor, then let his arm fall. Nat led his men along the half-dark passage.

At the end of the corridor two more guards were on duty, but one was collapsed upon the floor, apparently unconscious, and the other, making a feeble attempt to draw his ray-rod, crumbled into ashes as Brent fired. The five burst through the door.

They found themselves in the banquet-hall. The remnants of the meal were still upon the table, and three Moon men, looking as if they had been poisoned, were writhing on the floor. At the farther end of the hall was another door.

This gave upon a central hall, with a door in each of its four sides, and a blaze of sunlight coming through the crystal roof. The five stopped, baffled. Then of a sudden Axelson's voice broke the silence—his voice, yet changed almost beyond recognition, hoarse, broken, and gasping:

"Try the doors, Nathaniel Lee. Try each door in turn, and then go back. And know that in an instant I can blast you to nothingness where you stand!"

And suddenly there came Madge's voice, "He can't! He can't, Nat. He's dying, and he knows it. I won't let him, and he hasn't got the strength to move."

"Which door?" cried Nat in desperation.

"None of the doors. They're a trick," came Madge's voice. "Go forward and press the grooved panel upon the wall in front of you."

at stepped forward, found the panel, and pressed it. The wall swung open, like two folded doors, revealing another room within, perfectly circular.

It contained a quantity of pieces of apparatus, some glowing with light, some dark, and a radio transmitting set; it was evidently the secret lair of the Black Caesar. And there he was, trapped at last by the mortal illness that had overtaken him!

He was lying upon the couch, his great form stretched out, his features hideously swollen by the same disease that had attacked the guards.

Nat raised his ray-rod, but Axelson feebly put up his hand, and Nat lowered the weapon. And, as the five gathered about the dying man, again Nat felt that strange sense of pathos and pity for him.

He had never known Earth life, and he was not to be measured by the common standards applicable on Earth.

"Don't fire, Nat," said Madge in a shaky voice. She was seated beside Axelson, and—the wonder of it—she was sponging the foam from his lips and moistening his forehead. She raised a crystal that contained some fluid to his lips, and he drained it greedily.

"So—Earth wins, Nathaniel Lee," whispered Axelson hoarsely. "I am dying. I know it. It is the same dreaded disease that came to the Moon at the time of my father's landing there. Three-fourths of the Moon animals died. It is mortal. The lungs burn away.

"My father told me that on Earth it is not mortal. He called it 'cold'—but I am burning hot."

Then only did Nat understand, and the irony of it made him catch his breath and grit his teeth to check his hysterical laughter. The Black Caesar, the terror of Earth, was dying of a common cold which he himself had given him.

The coryza germ, almost harmless on Earth, among a population habituated to it for countless generations, had assumed the potency of a plague here, where no colds had ever been known—among the Moon men, and even among the guards, after their lifetime in the germless climate of Eros.

"I've failed, Nathaniel Lee," came the Black Caesar's voice. "And yet that hardly troubles me. There is something more that I do not understand. She is a creature like ourselves—with will and reason. She is not like the Moon women. She told me that she did not wish to be queen of the Earth because she did not love me. I do not understand. And so—I am glad to go."

gasp came from Axelson's throat as he raised his head and tried to speak, but the death-rattle was already in his throat. A slight struggle, and the massive form upon the couch was nothing but inanimate clay.

Madge rose from beside him, and the tears were streaming down her face.

"He wasn't a bad man, Nat," she said. "He was—gentle with me. He didn't understand; that was all. When I refused to be his queen, he was overcome with bewilderment. Oh, Nat, I can never, never write this story for the Universal News Syndicate."

Nat led her, sobbing, from the room.

Soon he succeeded in getting into teleradio communication with Earth. He broadcast the news that the Black Caesar was dead, and that his power for evil was at an end forever.

Then, in the few hours of daylight that remained, he set his men to work to smash the ray outfit that had destroyed China. There was some principle involved which he did not altogether understand, though Brent professed to have a clue to it, but it was evident that, except for the ray, Axelson had possessed no knowledge superior to that of the Earth scientists.

Of the guards, a few were already recovering, principally those of comparatively younger age. Not a Moon man, on the other hand, had survived the epidemic. As soon as Nat had got the guards out of the house, he reduced it to ashes by the aid of an old-fashioned box of phosphoric matches.

As the dark satellite was again creeping over Eros, the black ship set sail.

ut of the return journey to the Moon, where they transferred to their own ship, of their landing at New York, and of the triumphal reception that was accorded them, this is no place to speak. Nat's journey with Madge from the center of the city, in what was the old Borough of Westchester, to his home in the suburb of Hartford, was a continual ovation.

Crowds lined the air-route, and every few miles, so thick was the air-traffic, he was forced to hover and address the cheering multitudes. Hartford itself was en fete, and across the main road the City Bosses had hung an old-fashioned banner, strung from house to house on either side, bearing the legend: For World President: NATHANIEL LEE!

Nat turned to Madge, who was seated beside him silently. "Ever hear of 'getting married?'" he asked.

"Of course I've heard of it," replied the girl indignantly. "Do you think I'm as dumb as that, Nat Lee? Why, those old-fashioned novels are part of the public schools' curriculum."

"Pity those days can't come back. You ought to be a World Presidentess, you know," said Nat. "I was thinking, if we registered as companionates, I could take you into the White House, and you'd have a swell time there taking X-rays on visiting days."

"Well," answered Madge slowly. "I never thought of that. It might be worth trying out."