In all the solar system there is no city quite like Mercis, capital of Mars. Solis, on Venus, is perhaps more beautiful, some cities of Earth certainly have more drive and dynamitism, but there is a strange inscrutable air about Mercis which even terrestials of twenty years' residence cannot explain. Outwardly a tourists' mecca, with white plastoid buildings, rich gardens, and whispering canals, it has another and darker side, ever present, ever hidden. While earthmen work and plan, building, repairing, bringing their vast energy and progress to decadent Mars, the silent little reddies go their devious ways, following ancient laws which no amount of terrestial logic can shake. Time-bound ritual, mysterious passions and hates, torturous, devious logic ... all these, like dark winding underground streams run beneath the tall fair city that brings such thrilled superlatives to the lips of the terrestial tourists.

Steve Ranson, mounting the steps of the old house facing the Han canal, was in no mood for the bizarre beauties of Martian scenery. For one thing, Mercis was an old story to him; his work with Terrestial Intelligence had brought him here often in the past, on other strange cases. And for another thing, his mission concerned more vital matters. Jared Haller, as head of the state-owned Martian Broadcasting System, was next in importance to the august Governor Winship himself. As far back as the Hitlerian wars on earth it had been known that he who controls propaganda, controls the nation ... or planet. Martian Broadcasting was an important factor in controlling the fierce warlike little reddies, keeping the terrestial-imposed peace on the red planet. And when Jared Haller sent to Earth for one of the Terrestial Intelligence, that silent efficient corps of trouble-shooters, something was definitely up.

The house was provided with double doors as protection against the sudden fierce sandstorms which so often, in the month of Tol, sweep in from the plains of Psidis to engulf Mercis in a red choking haze. Ranson passed the conventional electric eye and a polite robot voice asked his name. He gave it, and the inner door opened.

A smiling little Martian butler met him in the hall, showed him into Haller's study. The head of M.B.C. stood at one end of the big library, the walls of which were lined with vivavox rolls and old-fashioned books. As Ranson entered, he swung about, frowning, one hand dropping to a pocket that bulged unmistakably.

"Ranson, Terrestial Intelligence." The special agent offered his card. "You sent to Earth a while ago for an operator?"

Jared Haller nodded. He was a big, rough-featured individual with gray leonine hair. A battering-ram of a man, one would think, who hammered his way through life by sheer force and drive. But as Ranson looked closer, he could see lines of worry, of fear, etched about the strong mouth, and a species of terror within the shaggy-browed eyes.

"Yes," said Jared Haller. "I sent for an operator. You got here quickly, Mr. Ranson!"

"Seven days out of earth on the express-liner Arrow." Ranson wondered why Haller didn't come to the point. Even Terrestial Intelligence headquarters in New York hadn't known why a T.I. man was wanted on Mars ... but Haller was one of the few persons sufficiently important to have an operator sent without explanation as to why he was wanted. Ranson put it directly. "Why did you require the help of T.I., Mr. Haller?" he asked.

"Because we're up against something a little too big for the Mercian police force to handle." Jared Haller's strong hands tapped nervously upon the desk. "No one has greater respect for our local authorities than myself. Captain Maxwell is a personal friend of mine. But I understood that T.I. men had the benefit of certain amazing devices, remarkable inventions, which make it easy for them to track down criminals."

Ranson nodded. That was true. T.I. didn't allow its secret devices to be used by any other agency, for fear they might become known to the criminals and outlaws of the solar system. But Haller still hadn't told what crime had taken place. This time Ranson applied the spur of silence. It worked.

"Mr. Ranson," Haller leaned forward, his face a gray grim mask, "someone, something, is working to gain control of the Martian Broadcasting Company! And I don't have to tell you that whoever controls M.B.C. controls Mars! Here's the set-up! Our company, although state owned, is largely free from red-tape, so long as we stress the good work we terrestials are doing on Mars and keep any revolutionary propaganda off the air-waves. Except for myself, and half a dozen other earthmen in responsible positions, our staff is largely Martian. That's in line with our policy of teaching Mars our civilization until it's ready for autonomy. Which it isn't yet, by quite some. As you know."

Ranson nodded, eyes intent as the pattern unfolded.

"All right." Haller snapped. "You see the situation. Remove us ... the few terrestials at the top of M.B.C ... and Martian staff would carry on until new men came out from Earth to take our places. But suppose during that period with no check on their activities, they started to dish out nationalist propaganda? One hour's program, with the old Martian war-songs being played and some rabble-rouser yelling 'down with the terrestial oppressors' and there'd be a revolution. Millions of reddies against a few police, a couple of regiments of the Foreign Legion. It'd be a cinch."

"But," ... Ranson frowned ... "this is only an interesting supposition. The reddies are civilized, peaceful."

"Outwardly," Haller snapped. "But what do you or any other earthmen know about what goes on in their round red heads? And the proof that some revolt is planned lies in what's been happening the past few weeks! Look here!" Haller bent forward, the lines about his mouth tighter than ever. "Three weeks ago my technical advisor, Rawlins, committed suicide. Not a care in the world, but he killed himself. A week later Harris, head of the television department, went insane. Declared a feud with the whole planet, began shooting at everyone he saw. The police rayed him in the struggle. The following week Pegram, the musical director, died of a heart attack. Died with the most terrorized expression on his face I've ever seen. Fear, causing the heart attack, his doctor said. You begin to see the set-up? Three men, each a vital power in M.B.C. gone within three weeks! And who's next? Who?" Jared Haller's eyes were bright with fear.

"Suicide, insanity, heart attack." Ranson shrugged. "All perfectly normal. Coincidence that they should happen within three weeks. What makes you think there's been foul play?"

For a long brittle moment Jared Haller stared out at the graceful white city, wan in the light of the twin moons. When he turned to face Ranson again, his eyes were bleak as a lunar plain.

"One thing," he said slowly. "The music."

"Music?" Ranson echoed. "Look here, Mr. Haller, you...."

"It's all right." Jared Haller grinned crookedly. "I'm not insane. Yet. Look, Mr. Ranson! There's just one clue to these mysterious deaths! And that's the music! In each instance the servants told of hearing, very faintly, a strange melody. Music that did queer things to them, even though they could hear it only vaguely. Music like none they'd ever heard. Like the devil's pipes, playing on their souls, while.... Almighty God!"

Jared Haller froze, his face gray as lead, his eyes blue horror. Ranson was like a man in a trance, bent forward, lips pressed tight until they resembled a livid scar. The room was silent as a tomb; outside, they could hear the vague rumbling of the city, with the distant swish of canal boats, the staccato roar of rockets as some earth-bound freighter leaped from the spaceport. Familiar, homey sounds, these, but beneath them, like an undercurrent of madness, ran the macabre melody.

There was, there had never been, Ranson knew, any music like this. It was the pipes of Pan, the chant of robots, the crying of souls in torment. It was a cloudy purple haze that engulfed the mind, it was a silver knife plucking a cruel obligato on taut nerves, it was a thin dark snake writhing its endless coils into the room.

Neither man moved. Ranson knew all the tricks of visual hypnotism, the whirling mirror, the waving hands, the pool of ink ... but this was the hypnotism of sound. Louder and clearer the music sounded, in eerie overtones, quavering sobbing minors, fierce reverberating bass. Sharp shards of sound pierced their ears, deep throbbing underrhythm shook them as a cat shakes a mouse.

"God!" Haller snarled. "What ... what is it?"

"Don't know." Ranson felt a queer irritation growing within him. He strode stiffly to the window, peered out. In the darkness, the broad Han canal lay placid; the stars caught in its jet meshes gently drifted toward the bank, shattered on the white marble. Along the embankment were great fragrant clumps of fayeh bushes. It was among these, he decided, that their unknown serenader lay concealed.

Suddenly the elfin melody changed. Fierce, harsh, it rose, until Ranson felt as though a file were rasping his nerves. He knew that he should dash down, seize the invisible musician below ... but logic, facts and duty, all were fading from his mind. The music was a spur, goading him to wild unreasoning anger. The red mists of hate swirled through his brain, a strange unreasoning bloodlust grew with the savage beat of the wild music. Berserk rage sounded in each shivering note and Ranson felt an insane desire to run amok. To inflict pain, to see red blood flow, to kill ... kill! Blindly he whirled, groping for his gun, as the music rose in a frenzied death-wail.

Turning, Ranson found himself face to face with Jared Haller. But the tall flinty magnate was now another person. Primitive, atavistic rage distorted his features, insane murder lurked in his eyes. The music was his master, and it was driving him to frenzy. "Kill!" the weird rhythm screamed, "Kill!" And Jared Haller obeyed. He snatched the flame-gun from his pocket, levelled it at Ranson.

Whether it was the deadly melody outside, or the instinct of self-preservation, Ranson never knew, but he drove at Haller with grim fury. The flame-gun hissed, filling the room with a greenish glare, its beam passing so close to Ranson's hair as to singe it. Ranson came up, grinning furiously, and in a moment both men were struggling, teeth bared in animalistic grins, breath coming in choked gasps, whirling in a mad dance of death as the macabre music distilled deadly poison within their brains.

The end came with startling suddenness. Ranson, twisting his opponent's arm back, felt the searing blast of the flame-gun past his hand. Jared Haller, a ghastly blackened corpse, toppled to the floor.

At that moment the lethal rhythm outside changed abruptly. From the fierce maddening beat of a few minutes before, the chords took on a yearning seductive tone. A call, it seemed, irresistible, soft, with a thousand promises. This was the song the sirens sang to Ulysses, the call of the Pied Piper, the chant of the houris in paradise. It conjured up pictures in Ranson's mind ... pictures of fairyland, of exquisitely beautiful scenes, of women lovely beyond imagination. All of man's hopes, man's dreams, were in that music, and it drew Ranson as a moth is drawn to a flame. The piping of Pan, the fragile fantasies of childhood, the voices of those beyond life.... Ranson walked stiffly toward the source of the music, like a man drugged.

As he approached the window the melody grew louder. The hypnotism of sound, he knew, but he didn't care. It was enthralling, irresistible. Like a sleepwalker he climbed to the sill, stood outlined in the tall window. Twenty feet to the ground, almost certain death ... but Ranson was lost in the golden world that the elfin melody conjured up. He straightened his shoulders, was about to step out.

Then suddenly there was a roar of atomic motors, a flashing of lights. A police boat, flinging up clouds of spray, swept up the canal, stopped. Ranson shook himself, like a man awakening from a nightmare, saw uniformed figures leaping to the bank. From the shadow of the fayeh bushes a slight form sprang, dodged along the embankment. Flame-guns cut the gloom but the slight figure swung to the left, disappeared among the twisting narrow streets. Bathed in cold sweat, Ranson stepped back into the room, where the still, terrible form of Jared Haller lay. Ranson stared at it, as though seeing it for the first time. Outside, there were pounding feet; the canal-patrolmen raced through the house, toward the study. And then, his brain weary as if it had been cudgelled, Ranson slid limply to the floor.

Headquarters of the Martian Canal-Patrol was brilliantly lighted by a dozen big astralux arcs. Captain Maxwell chewed at his gray mustache, staring curiously at Ranson.

"Then you admit killing Haller?" he demanded.

"Yes." Ranson nodded sombrely. "In the struggle. Self-defense. But even if it hadn't been self-defense, I probably would have fought with him. That music was madness, I tell you! Madness! Nobody's responsible when under its influence! I...."

"You killed Haller," Captain Maxwell said. "And you blame it on this alleged music. I might believe you, Ranson, but how many other people would? Even members of Terrestial Intelligence aren't sacro sanct. I'll have to hold you for trial."

"Hold me for trial?" Ranson leaned forward, his gaunt face intent. "While the real killer, the person playing that music, gets away? Look! Let me out of here for twelve hours! That's all I ask! And if I don't track down whoever was outside Haller's house, you can...."

"Sorry." Captain Maxwell shook his head. "You know I'd like to, Ranson. But this is murder. To let a confessed murderer, even though he is a T.I. man, go free, is impossible." The captain drew a deep breath, motioned to the two gray-uniformed patrolmen. "Take Mr. Ranson."

And then Steve Ranson went into action. In one blinding burst of speed, he lunged across the desk, tore Captain Maxwell's pistol from its holster. Before the captain and the two patrolmen knew what had happened, they were staring into the ugly muzzle of the flame-gun.

"Sorry." Ranson said tightly. "But it had to be done. There's hell loose on Mars, the devil's melody! And it's got to be stopped before it turns this planet upside down!"

"You can't get away with this, Ranson!" Captain Maxwell shook his head. "It'll only make it tougher for you when we nab you again! Be sensible! Put down that gun."

"No good. Got to work fast." Ranson backed toward the door, gun in hand. "Let this mad music go unchecked and it's death to all terrestials on Mars! And I'm going to stop it! So long, captain! You can try me for murder if you want, after I've done my job here!"

Ranson took the key from the massive plastic door as he backed through the entrance. Once in the hall, he slammed the door shut, locked Maxwell and his men in the room. Then, dropping the gun into his pocket, he ran swiftly down the corridor to the main entrance of headquarters. In the hall a patrolman glanced at him suspiciously, halted him, but a wave of Ranson's T.I. card put the man aside.

Free of headquarters, Ranson began to run. Only a few moments, he knew, before Maxwell and his men blasted a way to freedom, set out in pursuit. Like a lean gray shadow Ranson ran, twisting, dodging, among the narrow streets, heading toward Haller's house. Mercis was a dream city in the wan light of the moons. One in either side of the heavens, they threw weird double shadows across the rippling canals, the aimless streets. Sleek canal-cabs roared along the dark waterways, throwing up clouds of spray, and on the embankments, green-eyed, bulge-headed little reddies padded, silent, inscrutable, themselves a part of the eternal mystery of Mars.

Haller's house stood dark and brooding beside the canal. Captain Maxwell's men had completed their examination and the place was deserted. Ranson stepped into the shadow of the clump of fragrant fayeh bushes, where the unknown musician had stood; there was little danger, he felt, of patrolmen hunting for him at Haller's house. The captain had little faith in copybook maxims about the murderer returning to the scene of the crime.

Ranson stood motionless for a moment as a canal boat swept by, then drew from his pocket a heavy black tube. He tugged, and it extended telescopically to a cane some four feet long. The cane was hollow, a tube, and the head of it was large as a man's two fists and covered with small dials, gauges. This was the T.I.'s most cherished secret, the famous "electric bloodhound," by which criminals could be tracked.

Ranson touched a lever and a tiny electric motor in the head of the cane hummed, drawing air up along the tube. He tapped the bank where the unknown musician had stood, eyes on the gauges. Molecules of matter, left by the mysterious serenader, were sucked up the tube, registered on a sensitive plate, just as delicate color shades register on the plate of a color camera.

Ranson tapped the cane carefully upon the ground, avoiding those places where he had stood. Few people crossed this overgrown embankment, and it was a safe bet that no one other than the strange musician had been there recently. The scent was a clear one, and the dials on the head of the cane read R-2340-B, the numerical classification of the tiny bits of matter left behind by the unknown. The theory behind it was quite simple. The T.I. scientists had reasoned that the sense of smell is merely the effect of suspended molecules in the air acting upon sensitive nerve filaments, and they knew that any normal human can follow a trail of some strong odor such as perfumes, or gasoline, while animals, possessing more sensitive perceptions, can follow less distinct trails. To duplicate this mechanically had proven more difficult than an electric eye or artificial hearing device, but in the end they had triumphed. Their efforts had resulted in the machine Ranson now carried.

The trial was, at the start, clear. Ranson tapped the long tube on the ground like a blind man, eyes on the dial. Along the embankment, into a side street, he made his way. There were few abroad in this old quarter of the city; from the spaceport came the roar of freighters, the rumble of machinery, but here in the narrow winding streets there was only the faint murmur of voices behind latticed windows, the rustle of the wind, the rattle of sand from the red desert beyond the city.

As Ranson plunged further into the old Martian quarter, the trail grew more and more confused, crossed by scores of other trails left by passersby. He was forced to stop, cast about like a bloodhound, tapping every square foot of the street before the R-2340-B on the dial showed that he had once more picked up the faint elusive scent.

Deeper and deeper Ranson plunged into the dark slums of Mercis. Smoky gambling dens, dives full of drunken spacehands and slim red-skinned girls, maudlin singing ... even the yellow glare of the forbidden san-rays, as they filtered through drawn windows. Unsteady figures made their way along the streets. Mighty-thewed Jovian blasters, languid Venusians, boisterous earthmen ... and the little Martians padding softly along, wrapped in their loose dust-robes.

At the end of an alley where the purple shadows lay like stagnant pools, Ranson paused. The alley was a cul-de-sac, which meant that the person he was trailing must have entered one of the houses. Very softly he tapped the long tube on the ground. Again with a hesitant swinging of dials, R-2340-B showed up, on the low step in front of one of the dilapidated, dome-shaped houses. Ranson's eyes narrowed. So the person who had played the mad murder melody had entered that house! Might still be there! Quickly he telescoped the "electric bloodhound," dropped it into his pocket, and drew his flame-gun.

The old house was dark, with an air of morbid deadly calm about it. Ranson tried the door, found it locked. A quick spurt from his flame-gun melted the lock; he glanced about to make sure no one had observed the greenish glare, then stepped inside.

The hallway was shadowy, its walls hung with ancient Martian tapestries which, from their stilted symbolic ideographs must have dated back to the days of the Canal-Builders. At the end of the hallway, however, light jetted through a half-open door. Ranson moved toward it, silent as a phantom, muscles tense. Gripping his flame-gun, he pushed the door wide ... and a sudden exclamation broke from his lips.

Before him lay a gleaming laboratory, lined with vials of strange liquids, shining test-tubes, and queer apparatus. Beside a table, pouring a black fluid from a beaker into a test-tube, stood a man. Half-terrestial, half-Martian, he seemed, with the large hairless head of the red planet, and the clean features of an earthman. His eyes, behind their glasses, were like green ice, and the hand pouring the black fluid did not so much as waver at Ranson's entrance.

Ranson gasped. The bizarre figure was that of Dr. Elath Taen, master-scientist, sought by the T.I. for years, in vain! Elath Taen, outlaw and renegade, whose sole desire was the extermination of all terrestials on Mars, a revival of the ancient glories of the red planet. The tales told about him were fabulous; and this was the man behind the unholy music!

"Good evening, Mr. Ranson," Elath Taen smiled. "Had I known T.I. men were on Mars I should have taken infinitely more precautions. However...."

As he spoke, his hand moved suddenly, as though to hurl the test tube at Ranson. Quick as he was, the T.I. man was quicker. A spurt of flame leapt from his gun, shattering the tube. The dark liquid hissed, smoking, on to the floor.

"Well done, Mr. Ranson." Elath Taen nodded calmly. "Had the acid struck you, it would have rendered you blind."

"That's about enough of your tricks!" Ranson grated. "Come along, Dr. Taen! We're going to headquarters!"

"Since you insist." Elath Taen removed his chemist's smock, began, very deliberately, to strip off his rubber gloves.

"Quit stalling!" Ranson snapped. "Get going! I...." The words faded on the T.I. man's lips. Faintly, in the distance, came the strains of soft eerie music!

"Good God!" Ranson's eyes darted about the laboratory. "That ... that's the same as Haller and I...."

"Exactly, Mr. Ranson." Elath Taen smiled thinly. "Listen!"

The music was a caress, soft as a woman's skin. Slow, drowsy, like the hum of bees on a hot summer's afternoon. Soothing, soporific, in dreamy, crooning chords. A lullaby, that seemed to hang lead weights upon the eyelids. Audible hypnotism, as potent as some drug. Clearer with each second, the melody grew, coming nearer and nearer the laboratory.

"Come ... come on," Ranson said thickly. "Got to get out of here."

But his words held no force, and Elath Taen was nodding sleepily under the influence of the weird dream-music. Ranson knew he should act, swiftly, while he could; but the movement of a single muscle seemed an intolerable effort. His skin felt as though it were being rubbed with velvet, a strange purring sensation filled his brain. He tried to think, to move, but his will seemed in a padded vise. The music was dragging him down, down, into the gray mists of oblivion.

Across the laboratory Elath Taen had slumped to the floor, a vague smile of triumph on his face. Ranson turned to the direction of the music, tried to raise his gun, but the weapon slipped from his fingers, he fell to his knees. Sleep ... that was all that mattered ... sleep. The music was like chloroform, its notes stroked his brain. Through half-shut eyes he saw a door at the rear of the laboratory open, saw a slim, dark, exotic girl step through into the room. Slung about her neck in the manner of an accordian, was a square box, with keys studding its top. For a long moment Ranson stared at the dark, enigmatic girl, watched her hands dance over the keys to produce the soft lulling music. About her head, he noticed, was a queer copper helmet, of a type he had never before seen. And then the girl, Elath Taen, the laboratory, all faded into a kaleidoscopic whirl. Ranson felt himself falling down into the gray mists, and consciousness disappeared.

Steve Ranson awoke to find himself still in the laboratory, bound securely hand and foot. Opposite him Elath Taen was just struggling to his feet, aided by the dark-haired, feline girl.

"I ... I'm all right, Zeila," Taen muttered. "It was necessary that I, also, hear the sleep-melody, in order to overcome our snooping friend here. But look—he's coming to!"

The girl's gold-flecked eyes turned to Ranson, studied him impassively. Elath Taen gave a mocking smile.

"My daughter Zeila, Mr. Ranson," he murmured. "The consolation of my declining years. She, too, has devoted her life to the great cause of Martian freedom, the overthrow of Terra!"

"To be expected from your daughter," Ranson grunted. "I might have known you were at the bottom of this, Taen! Killing off the officials of the Martian Broadcasting Company!"

"Killing?" Taen smiled, glanced at the queer box slung about the girl's neck. "We only serenaded them. Induce the necessary moods for murder, suicide, madness. You have played our tunes to the remaining two, Zeila?"

The girl nodded impassively. "Cartwright unfortunately ended his own life," she said. "Rankin heard the song of hate, went berserk and was killed. Yla-tu, one of our own people, is in charge of M.B.C. until more terrestial executives arrive from earth."

"By which time we will have played our melodies to all Mars," Taen murmured. "One swift, merciless uprising, and the red planet is free! An hour or so over M.B.C.'s network...."

"You're nuts!" Ranson laughed. "If you think...."

"I don't think," Elath Taen smiled. "I know, Mr. Ranson. Before the night is out, all terrestials on Mars will be imprisoned or dead. Our people need only something to awaken them, to arouse their hate! And I can do that! I am the master of moods!" He took a copper helmet similar to the one the girl wore, from a shelf, placed it on his head. "A shield against supersonics," he explained. "It produces vibrations which nullify those set up by the sonovox." He faced the langorous Zeila. "Play, child! Convince Mr. Ranson of our powers!"

Again the girl's fingers danced over the keys in a wild melody of hate. Red mists rose before Ranson's eyes and he fought against the bonds that held him. Then the song changed to a dirge-like melody and Ranson fell into the black abyss of despair. This was more than music, he knew; it was something deeper that played upon the soul. Again the notes changed and crawling fear enveloped Ranson until he felt sick with horror of the unknown. Emotion after emotion gripped him, and had he not been helpless, bound, he would have obeyed the moods that swept his brain. He was himself like an instrument upon which a thousand tunes were played ... and through it all Elath Taen smiled with a vague detached air, while the girl's eyes burned into his own.

Suddenly Elath Taen raised his hand. "Enough, Zeila," he said. "He is exhausted."

The music ceased and Ranson fell back weakly, worn by the storm of emotions that had surged in waves over him.

"You.... You win!" he gasped. "What kind of deviltry is this?"

"Deviltry?" Dr. Taen laughed. "But it is so simple. Music, even normal music, can produce moods. The uplift of the ancient earthsong, 'Marsailles,' the melancholy of the 'Valse Triste,' the passion of the 'Bolero.' Indeed, many years ago on Terra, there was a strange song entitled, 'Gloomy Sunday,' which caused numerous suicides on the part of those who heard it. As for the instrument, it's merely an electrical sound producer such as your electric organ, theremins, and so on. But to it I have added a full range of supersonic notes, which, though inaudible, are the real mood-changers."

"Supersonics?" Ranson exclaimed. "You mean they're what created the emotions inside me just now?"

"Exactly." Elath Taen nodded. "The audible music helps, but it is the supersonics that determine the emotions! Their effect is upon the brain, and nothing can shut them out except counter-notes such as are set up by our helmets!" He tapped the copper dome that encased his head. "The effects of supersonics upon the emotions is interesting, Mr. Ranson. I first got my idea from old twentieth-century records on Terra itself. I read how, in the days of motion pictures before television was perfected, one of your Hollywood companies introduced a supersonic note onto the sound-track of a film in hopes of creating an atmosphere of horror at a certain point in the picture. But so great was the terror induced at the private showing that the supersonic note was immediately cut from the sound-track, and the records of the case filed away. It was the discovery and study of these records that started me on the trail of super-music. Thus with cosmic irony, Mr. Ranson, Earth has created the weapon which will destroy her! Supersonics!"

Ranson stared at Elath Taen, bewildered. Supersonics creating emotions! That was what had infuriated Haller and himself, had driven the other officials of M.B.C. to various forms of death! And now, with M.B.C. in the hands of Taen's followers, they planned to arouse the silent little reddies of Mars to revolt!

"But why?" Ranson demanded. "Earthmen have brought new life, new progress to Mars! We've built roads, canals, spaceports, taught your people our science...."

"You are aliens!" Elath Taen cried. "You must be wiped out!" He drew a whistle from his pocket, blew a shrill blast. There was a pattering of feet, and a squat Martian, his arms scarred by flame-gun burns, entered the room.

"Place the terrestial in safe keeping," Elath Taen commanded. "Watch him well." He glanced at the blinking red light of a time-signal on the wall. "Come Zeila! It's time to go!"

The girl nodded, picked up the sonovox. At the door she paused, glanced back at Ranson.

"Music for the men of Mars," she murmured. "When we return our own people will rule this planet!" Her eyes, brooding on the earthman, were inscrutable. "Alotah, Stephen Ranson!"

Then she and her father had left the laboratory, and the burly guard was forcing Ranson toward a small iron-barred door at the rear of the room. Bound, helpless, he staggered into the cell, heard the door clang shut behind him. The scarred, ugly guard stationed himself across the laboratory, where he could keep an eye on the cell.

Ranson lay there in the shadows, suddenly bitter. A nice mess he'd made of things! Wanted for murder by Captain Maxwell, tricked by Elath Taen and his daughter when he had them in his grasp, and now a prisoner here, while they sent their musical madness, their deadly supersonic notes, over the planet-wide chain of M.B.C. Ranson knew what that would mean. Except for the Foreign Legion, a few rocket-plane squadrons, Mars was undefended. If Elath Taen's supersonics aroused the reddies to revolt, his dream of making himself emperor of Mars would be at last fulfilled.

Ranson shot a glance at his guard. The scarred little Martian was leaning back in his chair, eyes on the cell door. But it seemed unlikely that he could see what went on within the shadowy cell. In one swift movement the T.I. man smashed his wrist-watch against the wall, then, picking up a sliver of glass with his fingertips, began to saw at his bonds.

At length the ropes fell from Ranson's aching arms. Swiftly he freed his legs. The guard was still sitting in the well-lighted laboratory, unmoved. Ranson glanced at the door. Steel bars, impossible to penetrate. And seconds ticking away!

A dark fighting grin spread over Ranson's lean face. There was one chance. A wild, desperate chance, but if it worked.... Hastily he slipped off his shoes, placed them on the floor beside him. Then, thrusting his hand into his coat pocket, he bulged the cloth out with his finger to simulate a gun.

"Don't move!" he said in sibilant Martian. "Drop your flame-gun! Try anything and I'll shoot!"

The guard sprang to his feet, his bulging hairless head gleaming in the bright light, his green eyes cold with rage. As Ranson had expected, he gave no indication of surrender. Instead, he raised his weapon, fired.

At the moment that the guard pressed the trigger, the terrestial leaped to one side, seeking cover of the wall at the side of the door. A savage greenish flash spat from the gun, a terrible wave of heat swept the cell. Half-blinded, sick from the searing heat, Ranson lay in his corner and watched the door. Under the fiery blast, the iron bars turned white, ran, until only pools of molten metal lay between him and freedom.

The squat Martian snapped off the ray, approached the glowing door cautiously, to find out if there was life in Ranson's inert body. There was ... more than the little reddy had bargained for. The earthman's arm swung in an arc and one of his shoes, flying through the blasted, melted door, caught the little Martian's wrist, knocked the flame-gun from his hand. The other shoe, following swiftly, landed alongside his head, sent him reeling and staggering back into a shelf of test-tubes and beakers.

"And that's how we do it on Earth!" Grinning tightly, Ranson leaped the puddles of molten metal, plunged through the blasted, glowing remains of the door. Before the ugly little guard could recover, a hard knotted terrestial fist had slammed against his chin, sent him, limp and unconscious to the floor.

Before the ugly little guard could recover, a hard terrestial fist had slammed against his chin.

Swiftly Ranson ripped wires from the masses of intricate machinery, bound the inert reddy, then, snatching up the flame-gun, ran from the house.

Twisting, turning, he came to the embankment of the Psidian canal. A sleek water-cab slid into view, its atomic motors humming. Ranson hailed it, hand on his gun, but the wizened reddy at the wheel had apparently not heard of Elath Taen's mad melody.

"Martian Broadcasting Building," Ranson grated. "Step on it!"

The driver nodded, and, when his passenger was aboard, sent the boat surging along the canal, throwing up clouds of spray. Racing, roaring, dodging heavily-laden freight boats, the cab tore over the dark cold water that flowed, via the intricate networks of canals, from the polar caps.

As they neared the center of the city, the atmosphere of tension grew. Little bands of terrestial police patrolled the embankments, a squadron of rocket-planes droned above the towering metropolis, the light of their exhausts throwing weird shadows. Occasional shouts, the green flash of flame-guns, issued from the darkness and the crowds of reddies gathered before their radios in houses, shops, and public squares, were seething with excitement. The roar of the cab's motors drowned out the sound of the music and Elath Taen's exultant voice, but the driver moved uneasily.

"Looks like somethin's up," he muttered. "I'll see if we can get a bulletin."

Before Ranson could stop him, he had snapped on the radio within the cab. The wild, frenzied music filled the small cabin, tearing at both men's minds, while Taen's voice urged revolt. Then, under the influence of the supersonics, red flames of hatred leaped through their brains, banishing all thought, logic. The little Martian driver whirled about, only to have the butt of Ranson's gun crash down upon his head. Slumping forward, his body fell against the radio, shattering its fragile tubes. Ranson shook himself as the infernal music abruptly ceased.

The M.B.C. building lay just before them. Ranson swung the cab to the embankment, sprang out. The tall plastoid building towered white and spectral above the canal. Ranson burst through the door.

Several reddies on guard sprang forward, but a blast from the terrestial's gun cleared the great hall. He sprang into an elevator, jabbed at a button, and the car shot upward.

The elevator stopped at the top floor, where the broadcasting studios were located. Ranson hurtled along the corridor, plunged through the door. Before him lay a large room, blocked at one end by a thick, double-paned glass. And on the other side of the glass stood Elath Taen, crouched before a television set, his fingers running over the keys of the sonovox, his face exultant as he poured out the supersonics of his song of hate. Musical madness for the men of Mars, making them forget all that Terra had done for the red planet, driving them to insane mass murder! And as he played upon the sonovox, Taen spoke into the microphone, urging them to revolt! Already they were starting their reign of terror; when he reached his climax they would pour from their houses to kill all who had terrestial blood. Unless....

Ranson leaped forward. Even the supersonics were kept from the outer room by the vacuum-insulated double glass panes; Elath Taen was like a silent marionette in the broadcasting booth, his green eyes flickering with apprehension, his head encased by the shielding copper helmet.

"Drop your gun, Mr. Ranson!" Zeila's voice came from behind him.

Ranson whirled; the girl had been standing behind the door, unnoticed, as he burst into the room. Her exotic face was pale, but the flame-gun in her hand was steady. Ranson obeyed, smiling.

"As you wish," he said. "But T.I. has one trick we use as a last resort. Look!" From his pocket he drew a flat metal case. "Supposedly cigarettes, but really the most powerful explosive devised by our laboratories. Shoot me with that flame gun and the heat sets it off. You, your charming father, and I, will all be blown to atoms. So you won't dare shoot!"

Zeila stared at him, lips a crimson slash across her face.

"You won't get away with it!" she exclaimed. "It's bluff!"

"Shoot, then," Ranson said. "Blow the whole top of this building to bits!" He reached out for her gun.

The girl's eyes were fixed on the metal case, and there was fear in them. Ranson took another step toward her. Elath Taen could not watch since he was forced to keep his eyes on the intricate keyboard of the sonovox.

"Blown to bits," Ranson repeated sardonically. "Me, too, but at least I'll have removed the leaders of the revolt. This explosive is the last resort of T.I. men. Squeeze that trigger and the heat will set it off! Now give me that gun!"

Zeila Taen broke suddenly, shuddering at the thought of her vivid beauty torn to shreds by an explosion.

"Take it!" she snarled. "It's too late, anyhow! Mars is in revolt! No one can stop them now! Fool! My father will be emperor after the insurrection! You might have been prince."

Ranson didn't wait to hear more. One blast of the heat gun and the glass partition shattered to a thousand fragments.

"No good, Mr. Ranson." Elath Taen lifted his hands from the keyboard, smiling thinly. "The flame is lit and cannot be put out! The red flame of revolt! Already my people are fighting! Loud-speakers in every public square have carried the sound of mad, blind fury! I am the mood-master!"

"Get back to that sound-box!" Ranson grated. "Play those sleep-producing notes! Play, or I'll blast your lovely daughter here to a cinder! You claim you're the mood-master! Well, if your damned supersonics started this, they can end it!" He swung his gun to cover Zeila's sleek figure. "Play, Dr. Taen! I've never killed a woman yet, but it's her life or those of all terrestials on Mars! Back to your sonovox!"

For a long moment Elath Taen stared at his daughter, then nodded his hairless head somberly.

"Again you win, Mr. Ranson," he said softly. "I should have killed you or won you to my side, long ago." Turning to the sonovox, he began to play.

Ranson stood tense, covering the girl with his gun. Soft, lulling music, supersonic notes that seemed to caress his brain, filled the room. The drowsy sound of rain on a roof, of rustling leaves, of a soothing night wind ... all these were bound up in the melody. Peace, rest, sleep ... every nerve seemed to relax, every muscle seemed limp, as the dreamy musical hypnosis took effect.

Elath Taen and the girl were watching him covertly. There was a thin smile on the doctor's dark saturnine face. Dully Ranson tried to reason out why Elath Taen should be smiling, but somehow his mind refused to function. Those cloudy mists rising before his eyes! Miles away Taen was speaking, above the soporific sounds.

"Too bad," he was saying. "You forgot that whatever these supersonics may do to my people, they also affect you. Zeila and I are protected from the short-wave emanations by our helmets. But you, Mr. Ranson, are not! Already you are helpless and in a moment you will sleep, as you did in our laboratory! Then, with you secure, I shall arouse my people once more!"

Ranson tried to move, tried to act, but the music was a silken noose binding him, and he had no will power left. Sleep ... nothing else mattered.... As in a dream he saw Zeila coming toward him, felt himself crumple to the floor. Vaguely he remembered bright flashes, shouts, and then all was grey oblivion.

"Ranson! Ranson!" The words beat like fists upon his drugged brain.

The T.I. man stirred restlessly; out of the whirling mists Captain Maxwell's face became a stern reality.

"What happened?" the police officer was saying. "First the reddies go kill-crazy, then start passing out! Almost went nutty ourselves, down at headquarters, listening! But then the murder-music stopped and we heard your voice, talking to Elath Taen! So we came here pronto. Just in time."

"Taen! And Zeila!" Ranson gasped. "Where are they?"

"Gone." Captain Maxwell motioned to a door at the rear of the room. "Ducked out and down the elevator. Blasted the cables when they hit the bottom so we weren't able to follow." He shook his head. "You were right about that music! No wonder you and Haller went berserk! Don't worry about any trial for murder! Mars has been mad, this night!"

Ranson struggled to his feet. Taen and his daughter escaped! With the secret of the supersonic notes! But it would be a long time before they dared return to Mars. Still groggy, Ranson drew the metal cigarette case from his pocket.

"How were you able to force your way in here?" Captain Maxwell demanded. "To make them change the tune and break up the revolt?"

Ranson opened the metal case.

"Bluff," he said, taking a cigarette from the container and lighting it. "That's what saved Mars! Just ... bluff!"

Grinning, he blew a cloud of smoke.