“What caused you to answer our advertisement?” Owen Quest felt the steel of the quick gray eyes that jabbed like gimlets across the office table.

“Why does any man apply for a job?” he bristled.

Keane Clason gave an impatient smile.

“Come!” he said. “I’m not trying to snare you. But there were unusual features to my ad, and they were put there to attract an unusual type of man. To judge your qualifications, I must know just why this proposition appeals to you.”

“I can tell you that,” nodded Quest, “but there’s nothing unusual about it. In the first place, I knew that the Clason Research Corporation is the leading concern of its kind in the country. In the second place, this seemed to offer a way to obtain a substantial sum of money quickly.”

“Good,” said Clason. “And you feel that you have all the necessary qualifications?”

“Decidedly. I am 24 years old, athletic, and of an earnest and determined nature. Moreover, I have no family ties, and I’m willing to run any reasonable risk in order to improve the condition of my fellow men.”

Clason smiled his approval.

“You say you need money. How much immediately?”

Quest was unprepared for the question.

“A thousand dollars,” he ventured.

Without hesitation Clason counted out ten one-hundred-dollar notes from his wallet and laid them on the table.

“There’s your advance fee. You’re ready to go to work immediately, I hope?”

“Certainly,” stammered Quest.

Stunned by the swiftness of the transaction, he sat staring at the money that lay untouched before him.

To accept it would be like signing an unread contract. But he had asked for it; to refuse it was impossible. Even to delay about picking it up might arouse Clason’s suspicion. Already the latter had turned away and was opening the door of a steel cabinet. Quest had one second in which to reach a decision ... He crammed the currency into his pocket.

With delicate care Clason set two objects on the table. One looked to Quest like a miniature broadcasting tower or a mooring mast for lighter than air craft. The other was a circular vat of some black material, probably carbon. Within it a series of concentric tissues were suspended from metal rings, and in a trough outside ranged four stoppered flasks containing liquids of as many different colors.

“Look at these models carefully,” said Clason. “They represent two of the most remarkable discoveries of all time. The one on your left is the most destructive weapon known to man. The other I consider the most constructive discovery in the history of science. It may even lead to an understanding of the nature of life, and of the future of the spirit after death.

“Both of these were developed by my brother Philip and me together--but we have disagreed about the use to which they shall be put.

“Philip”--the inventor dropped his voice to a whisper--”wants to sell the secret of the Death Projector--the tower, there--as an instrument of war. If I should permit him to do that, it might lead to the destruction of whole nations!”

“How?” demanded Quest “I’ve heard of a device called the Death Ray. Is this it?”

“No, no,” said Clason contemptuously. “Even in a perfected state the Ray would be a child’s toy compared to the Projector. This is based on our discovery that invisible light rays of a certain wave-length, if highly concentrated, destroy life--and our additional discovery that if these are synchronized with short radio waves the effect is absolutely devastating.

“We obtain the desired concentration of invisible light by using a tellurium current-filter under the influence of alternate flashes of red and blue light. The projector can literally blanket vast areas with death, up to a top range of at least five hundred miles.

“Just picture to yourself what this means! In a space of ten minutes two men can lay down a circle of destruction a thousand miles in diameter; or they can cut a swath five hundred miles long in any desired direction.”

“Have you ever proved it?” demanded Quest skeptically.

“Yes, young man, we have,” snapped Clason. “Right here in the laboratory--but on a minute scale, of course. However, there’s no time to demonstrate now. The point is that my brother is determined to sell if he can obtain his price for the invention. He argues that instead of bringing disaster upon the world, this machine will forever discourage war by making it too terrible for any civilized nation to consider. In spite of my opposition he has opened negotiations with an ambitious Balkan power. He may actually close the sale at any moment!

“However,” Clason drew a deep breath “you see this other device? Simple as it appears, it is the key to the whole situation. We can use it--you and I--to overcome Philip’s will and prevent this unthinkable transaction. The two of us can do it. Alone I would be virtually helpless.”

“Why not have the Projector confiscated or destroyed by our own Government?” suggested Quest. “That seems to me the only safe and sure way out of the difficulty.”

“You simply do not understand,” frowned Clason impatiently. “Philip is selling the plans and descriptions of the machine, not the machine itself. Even if this model and the larger test machine that we have built were destroyed--even if I were willing to have Philip sent to Leavenworth for life--he could still sell the Projector.

“But this other invention, our Osmotic Liberator, makes it possible for me to gain control of Philip and actually change his mind, through the medium of an agent. I have hired you to act as my Agent, Quest, because I can see that you are a young man of unusual character and vitality. And by way of reward I can promise you both money and a brilliant future.”

The inventor poised in a tense attitude on the edge of his chair as though his body were charged with electricity. His eyes seemed to dart out emanations that set Quest’s blood to tingling. Then for a moment the latter lost consciousness of his physical self. It was as though he had opened a door and found himself suddenly on the brink of a new and totally strange world. He dispelled this fancy by a quick effort of the will, for he knew that he had a delicate problem on his hands and that it must be solved within a very few minutes. However he proceeded, he must act without disloyalty to his Government, and at the same time without injustice to Keane Clason.

“Tell me,” he said in a husky voice, “how do you intend to use me? I do not believe in Spiritualism. I would be a poor medium.”

Clason gave a short laugh.

“You are not to be a medium in that sense at all. Spiritualism as practiced is just a blind sort of groping and hoping. Osmotic Liberation, on the other hand, is an exact and opposite physico-chemical science. Here--I will show you.”

Into the outer cell of the Liberator he emptied the purple vial, and so on to the innermost, which he filled with a golden-green liquid like old Chartreuse.

“The separating membranes, you understand, are permeable by these complicated solutions. Each liquid has a different osmotic pressure and therefore should, under normal conditions, interchange with the others through the membranes until all pressures are equalized. I prevent such interchange, however, by maintaining an anti-electrolysis which retards ionization and thus builds up what might be called osmotic potential.

“Now if an Agent--yourself for instance--submerges himself in the central cell, at the same time maintaining a physical contact with his Control at the surface of the liquid, and if then the osmotic potential is suddenly released by throwing the electrolytic switch, the host of ions thus turned loose in the outer compartments make one grand rush for the center solution, which contains the cathode.

“Under these conditions your body becomes a sort of sixth cell, and your skin another membrane in the series. Properly speaking, however, you are not a part of the electrolytic circuit but are merely present in the action. Your body acts as a catalyser, hastening the chemical action without itself being affected in any way. Physically you undergo no change whatever; but in some strange way which is, like life, beyond analysis, your mind flows out into the solution, while your unaltered body remains at the bottom of the tank in a state of suspended animation.

“If no Control is present, all that is needed to return your mind into your body is a throw of the electrolytic switch back to negative, whereupon you emerge from the tank exactly as you entered it. But with your Control present and in contact with your submerged body, your mind, instead of remaining suspended in the solution, flows instantly into his body and resides there subject to his will.

“This can not be done, however, unless the wills of Control and Agent have first been brought into accord. To accomplish that, we clasp hands”--Quest grasped Clason’s extended hand--”and look steadily into each other’s eyes.

“Now, it is well known that the vibrations of an individual’s will are as distinctive as the sworls of his finger-prints. What is not so well known is that the frequency of vibration in one person can be brought into accord with that in another.

“You consciously retract your will by concentrating your mind upon the thing which you know I wish to accomplish. Gradually while we continue in this position your vibrations speed up or slow down until they acquire exactly the same frequency as my own. We are then in accord, and when your mind is liberated in the tank it is in a state which admits absorption into my body. And it is subject to my will because you have purposely attuned it to my peculiar frequency. Immediately after the transfer there will be a brief conflict, due to the instinctive desire of your will to obtain the ascendancy. But of course mine will gain the upper hand at once, since both wills will be in my frequency.”

Quest felt, rather than saw, a wall of alarm closing in on him. He tried to avert his eyes, to withdraw his hand from Clason’s grasp. With a nostalgic pang in the pit of his stomach he suddenly realized that he could not do so. He had gone too far--farther than any man in his position had a right to go. Having deliberately weakened his will, it seemed now to have deserted him entirely. A prickling sensation coursed up his spine, his extended arm went numb, his hand trembled violently.

“Splendid!” said Clason, suddenly releasing both eye and hand. “Just as I foresaw, you will be able to attune yourself to my vibration-frequency with hardly an effort. Now please remain seated; I’ll be back in a moment.”

For a second after the door closed, Quest remained slumped in his chair. Then he was on his feet, shaking himself like a wet dog to free himself from the spell under which he had fallen. Something about Clason attracted and at the same time repelled him, fraying his nerves like an irritant drug and confusing his mind at the moment when he needed the full alertness of every faculty.

Invisible light--disembodied minds--will vibrations! Nothing there to get hold of. Were these things real or imaginary? Was Keane Clason a great inventor, or a madman? Would Philip prove to be a real or an imaginary scoundrel? Should he summon help, or go on alone?

Professional pride said: wait, don’t be an alarmist! With his knuckles Quest tapped the table, half expecting it to melt under his fingers. The feeling and sound of the contact gave him a peculiar start. On the farther end of the table stood a letter-box--an invitation. From his pocket Quest snatched a slip of paper, and wrote:

6 stroke 4--9:45A--Hired. If no report in 48 hours, clamp down hard.

To address a stamped envelope and slip it in with the outgoing mail was the work of seconds. But he was none too quick. He had just dropped back into a lounging attitude when the door burst open and Clason flew into the room?

“We must act instantly,” hissed the inventor. “Philip plans to close the transaction within a day.”

In spite of himself, Quest jumped upright in his chair. Clason tapped him on the shoulder reassuringly.

“It’s all right,” he smiled, “I’m ready for him. We’ll make our move this afternoon and beat him by eighteen hours.

“Let’s see.” He paused. “Oh! yes. I was about to explain to you that as soon as the will of the Agent enters the body of his Control, the latter can again transfer it into the body of still another person.

“Now you understand why I advertised for a man of exceptional character? As my Agent, I want you to enter the body of Philip, and your will must be strong enough to conquer his in the battle for mastery which will begin the instant you intrude into his body. You will still be under my control, but your will must be strong enough on its own merits to overcome his. I can direct you, but your strength must be your own. That’s clear, isn’t it?”

“I think so,” said Quest slowly. “But what becomes of me after you have frustrated Philip’s plot?”

“That’s the easy part of the process,” smiled Clason; “but naturally you feel some anxiety about it. I simply withdraw your will from Philip, return it to your own body, and pay you a reward of ten thousand dollars.”

“You’re sure you can?”

“Perfectly. I have merely to touch Philip’s hand to recapture your will. Then I immerse myself in the tank with the switch at plus. The osmotic action will extract both wills momentarily from my body. But the presence of two bodies and two wills in the solution together forces a balance, and each will seeks out and enters its own body. Then you and I climb out of the tank exactly as we are this minute.”

“If it weren’t for my belief that anything is possible,” Quest shook his head, “I’d say that your claims for this invention were ridiculous.”

“And you couldn’t be blamed,” admitted Clason readily. “This toy of a model is hardly convincing. But come along with me and I’ll show you how the Liberator looks in actual operation.”

The office rug concealed a trap door which gave upon a spiral stair. Below, Clason unlocked another door and led the way through a narrow and tremendously long passage lighted at intervals by small electric bulbs. Presently another door yielded to the inventor’s deft touch and closed behind them with a portentous chug. Here the darkness was so utter and intense that Quest imagined he could feel the weight of it on his shoulders. From the slope of the passageway and the muffled beat of machinery that had come to his ears on the way along, he guessed that he was below ground in some chamber at the rear of the factory.

He gave a low exclamation as Clason switched on the toplight. No wonder the darkness had seemed of almost supernatural quality! Even the hard white glare of the daylight arc was grisly. Its rays rebounded from the liquids of the great circular tank in a blinding dazzle of color, while the dull black walls and ceiling were so perfectly absorptive that beyond arm’s length they became to all effects invisible. Even the ledge on which he stood--the shoulder of the vat--gave Quest the feeling that to move would be to step off into a bottomless pit.

But Clason took his attention at once, pointing here and there in his quick, nervous way to indicate how faithfully the Liberator had been reproduced from the model. In all respects the arrangements were the same, with the addition that here a long plank like a spring-board extended out from a wall-mount as far as the central compartment of the tank, and that from its end a narrow ladder hung down to the surface of the Chartreuse liquid. A double-throw switch fixed to the wall above the base of the plank was evidently the source of electrolytic control.

“When you throw the switch to plus,” said Clason, pointing to the chalk-marked sign above, “you produce the violent electrolytic action needed to bring about a liberation. All the rest of the time it should be closed at minus, in order to maintain the anti-action which I explained to you.

“Now let’s rehearse, so that when the time for the real performance arrives we can be sure of running it off without a hitch.”

“All right, sir,” nodded Quest, so dazed by the glittering light that he was hardly conscious of what he said.

“First,” said Clason, running lightly up the steps to the plank, “you walk out to the end, like this, and start down the ladder. Then you lower yourself into the tank. The liquid is at body temperature; it’s neither strongly acid nor caustic; it will cause you no injury or discomfort whatever.

“Meanwhile I keep in contact with your hand until the instant that you become submerged. Now your mind is in me, see?--ready for transfer into Philip, where it will act as my Agent. That’s how simple it is! Come on up and we’ll go through the motions.”

Quest experienced a shiver as he mounted the bridge. Annoyed with himself, he shrugged the feeling off. There was no risk here. Moreover, it was a part of his daily work to take chances; he had done so a hundred times without hesitation. Now he moved all the more quickly, as if to belie the squeamishness that possessed him in spite of himself.

Swinging past Clason on the plank, he lowered himself without a pause to the bottom rung of the ladder, while the inventor, hanging head down, maintained contact with him.

“No need to stay here,” he said in sudden irritation. “I understand perfectly what I am to do.”

“I’m testing my own acrobatic ability,” grunted Clason amiably. “Just a minute now.”

He wriggled as if trying to adjust himself to a better balance, but in reality to mask the motion of his free hand with which he reached up and pressed a button in the side of the plank. Instantly the structure, pivoting downward on its wall-socket, plunged Quest to his waist in the osmotic solution.

“For God’s sake get out of the way!” he shouted, trying to wrench his hand out of Clason’s sinewy grip. “Let go, I tell you!”

But Clason clung like a leech, his teeth gritted under the strain. Again the plank lurched downward, and with a violent splash Quest vanished below the surface.

Quick as a cat, Clason scrambled up the ladder and back to the base of the plank, where he erased and interchanged the chalk-marked signs with which he had misled Quest. Then with a sinister twist of a smile he threw the switch to minus, and turned to watch as the plank slowly righted itself and the vacant ladder came clear of the liquid.

For some time he stood staring at the gleaming colored rings of his dissociation-vat like some witch over her cauldron, his lips working, his hands clasping and unclasping like the tentacles of some sub-sea monster. Then, as if the spell had suddenly broken, he turned on his heel and switched off the light. As he hastened down the passageway toward his office, the airlock sucked the door against its jamb with an ominous whistle.

In a twinkling, as Quest’s shackled spirit writhed in its new housing, he knew that he was in bondage to a scoundrel. Formless and voiceless, he still fought madly for the freedom which the instinct of ten thousand generations made necessary to him.

At the same time he was furious at himself for having been tricked like an innocent schoolboy. The plank socket, the button which had tripped the supporting spring, the fake rehearsal, the tuning of his will to that of Clason--step by step the whole cunning scheme unfolded itself to him now.

But what could be the purpose behind this villainy? Only one answer seemed possible. Keane must be the one bent on selling the Death Projector, Philip the one who wished to frustrate the fiendish transaction! And Quest of the Secret Service--he was to be the tool to force the sale.

With the soundless scream of rage Quest’s will hurled itself against Keane’s. The two met like infuriated bulls, and for an instant too brief to be pictured as a lapse of time they poised immovable. But two wills can not exist on equal terms in a single body, and in this case the vibration of both was that of Clason. Quest had challenged the Master Will. He could do no more. It hurled him back, crushed him like foam, compressed him to the proportions of an atom in the background of his consciousness. So brief and unequal was the conflict that in the next breath Clason had all but forgotten the presence of the stolen will within him. When he was ready to use his Agent, that would be time enough to summon him!

Despite this suppression, Quest began to see dimly through strange eyes, and to hear vaguely with ears that were not his own. Feelers, tentacles, some intangible kind of conduits carried thought impulses to him from the Master Will. He received these impressions vividly, but those which he gave off in return were so weak, due to the subjection of his will, that Clason was entirely unconscious of any response. Quest was not enough of a scientist to be astonished at the ability of a disembodied mind to experience sense impressions in the body of another. He was only glad that the darkness and silence were growing less. Very, very slowly he was awakening to a new kind of consciousness--the consciousness of another person’s Self. He hated and loathed that Self, yet it was better than the awful blankness that had gone before.

Suddenly, as light grew brighter and sound more clear and definite, a new element entered--the element of hope. At first it was feeble: its only suggestion was that sometime, somehow, he might escape this prison. But it was like water to a parched plant. It caused his will to expand, to extend its feelers, to press up a little more bravely against the crushing pile of the Master Will.

Now another surprise sprang upon him. He was moving! That is, Clason’s body was moving in some kind of a conveyance, which was threading its way through crowded streets. Stores, buildings, buses, people--Quest remembered them all distantly as things he had known thousands of years ago. The driver turned his head, and his profile seemed vaguely familiar.

Now a rush of foreign thoughts drowned out his own. They were a sort of overflow from the mind of Clason. They thronged along the conduits that bound the two wills together, but only Quest was conscious of the movement.

Keane’s mind was on his brother Philip: that much was particularly clear. And there was something about a telephone call. Yes, Keane had telephoned to the police, disguising his voice, refusing to divulge his name. He had said that a man by the name of Philip Clason was in trouble and had told them where to find him. Then the police had telephoned the factory, and Keane had pretended astonishment and alarm at the news. That’s why he was here now--he was on the way to confer with the police. And he was chuckling--chuckling because he had fooled Quest and the police, and because now the hundred million dollars was almost in his grasp.

Cutting in close, the car turned a corner and drew up before one of a row of loft buildings in a section of the city which Quest failed to recognize. As Clason stepped to the sidewalk, Quest was more painfully aware than ever of his powerlessness to influence by so much as the twitch of a muscle the behavior of this hostile body in which he had permitted himself to be trapped. In his weakness he felt himself shrinking, contracting almost to nothingness under the careless pressure of the Master Will.

Clason glanced casually at his watch, and three men converged toward him from as many directions. There was nothing to distinguish them from anyone else in the street, but along the conduits it came to Quest that they were detectives and that they were there by appointment with Keane Clason.

“What floor?” asked the latter, with an excitement which Quest felt instantly was pure pretense. “Are you sure they haven’t spirited him away?”

“Don’t worry,” replied the leader of the detectives. “The alley and roof are covered. We’ll take care of the rest ourselves.”

On tiptoe they climbed three long flights of stairs in the half-light. Clason held back as if in fear. He was a good actor, and Quest felt the shrinking and hesitation of his body as he crouched and slunk along in the wake of the detectives, pretending terror at what was about to happen, though he knew--and Quest knew he knew--that there would be no resistance up there--that Philip would be found alone exactly as he had been left by Keane’s hired thugs.

On the top landing Burke, the leader, paused to count the doors from front to rear.

“This is it,” he whispered to the bull-necked fellow just behind him.

The other nodded, and crouched back against the opposite wall while his companions placed themselves in position to cross-fire into the room the moment the door gave way.

Quest longed for the power to kick his hypocrite of a master as he still held back, cowering on the stairs, playing his fake to the limit. Then the door flew in with a splintering shriek under the charge of the human battering ram, and across it hurtled the other two detectives in a cloud of ancient dust.

“Here he is!” someone shouted.

“Phil! Phil!” Keane Clason’s voice fairly quavered with sham emotion as he ran into the room and threw himself at a man tightly bound to an upholstered chair, which in turn was wedged in among other articles of stored furniture.

But Philip was too securely gagged to reply, and as Burke slashed the ropes from across his chest he dropped forward in a state of collapse. Stretched on a couch, he soon gave signs of response as a brisk massage began to restore the circulation to his cramped limbs. Suddenly he sat up and thrust his rescuers aside.

“What time is it?” he demanded with an air of alarm.

“One o’clock,” replied Keane before anyone else could answer, patting his brother affectionately on the shoulder while within him Quest writhed with indignation. “By Jove! Phil, it’s wonderful that we got to you in time. Really, how--you’re not injured?”

“No,” grunted Philip, “just lamed up. I’ll be as fit as ever by to-morrow.”

“If you feel equal to it,” suggested Burke, “I wish you’d tell me briefly how you arrived here. Do you know the motive behind this affair? Did you recognize any of the body-snatchers?”

Philip frowned and shook his head.

“Yesterday noon,” he said slowly, “I took the eight-passenger Airline Express to Cleveland on business. There were three other passengers in the cabin--two men and a woman. Right away I got out a correspondence file and was running over some letters. The next thing I knew I was approaching the ground in the strangest state of mind I ever experienced. My head was splitting, and everything looked unreal to me. Seemed as if I was coming down on some new planet.”

“You mean the ship was gliding down to land?”

“No, no. I was dangling from a parachute ... By the way, where am I now?”

“In a Munson Avenue loft.”

“In Chicago?”

Burke nodded.

“I guessed as much,” frowned Philip. “You see, I came down in a field, and then before I could free myself from my trappings I was pounced on--trussed up and blindfolded--by a gang of men. I knew they had taken me a long distance by automobile, but I saw nothing more until they tore the blindfold from my eyes when they left me here.”

“And they were all strangers to you?”

“Yes--those that I saw.”

“Isn’t this enough for just now, Burke?” interrupted Keane, and Quest received an impression of uneasiness that was not apparent in the inventor’s tone. “After a good rest he’s sure to recall things that escape him now.”

“Just one minute,” nodded the detective, turning back to Philip. “Can you think of no plausible reason for this attack? Is there no one who might possibly benefit by putting you temporarily out of the way?”

Philip gave a frightened start. Then he was on his feet, clutching at his brother’s arm.

“Keane!” he pleaded, “Keane! What’s happened? I know, I know! It’s the Projector.”

“Water!” roared Keane, and Quest felt the panic that coursed through him as he tried to drown out his brother. “Somebody bring water! He needs it!”

At the same time he snatched up Philip’s hand in a grip of steel. Instantly the latter’s wild eyes became calm, the flush passed from his relaxing face, and he slumped down weakly on the couch.

In that fleeting moment Quest surged into the body of Philip and confronted his will with a fierce and triumphant ardor. For now his will would have command of a body with which to fight his fiend of a Control.

With a sensation of contempt he met Philip’s resistance and buffeted him ruthlessly backward, crushed down and compressed his feebly struggling will. And as Philip yielded, Quest felt his own will expanding to normal, taking possession of the borrowed body with hungry greed, and flashing from its faded eyes the spark of youth.

Burke stared in amazement at the kaleidoscopic rapidity of the changes in the rescued man’s expression. Strange lights and shadows continued to flit across Philip’s face as Quest’s invasion of him proceeded, but with a diminishing frequency which soon assured Keane that his Agent was tightening his command.

The younger of Burke’s aides stood fascinated, his mouth agape. The other spoke guardedly to his superior: