he central structure of the group of buildings was shaped like a great plus-mark, each of its four wings of identical square construction, with long smooth metal sides and top, and with a door at the end giving entrance to a corridor that ran straight through to the chief central laboratory of Dr. Ku Sui.

Carse skimmed swiftly, two feet off the glittering metallic soil, towards the end of the nearest wing, where he gently landed. He tried the door giving entrance. It was open. He cautiously floated through into complete darkness.

The Hawk was prepared for that. He drew a hand-flash from the belt of his suit, and, standing motionless, his raygun ready in his left hand, he probed the darkness with a long white beam. Spaced evenly along the sides of the corridor were many identical doors, and at the end a larger, heavier door which gave entrance to the central laboratory. He found no life or anything that moved at all, so, methodically, he set about inspecting the side rooms.

The doors were all unlocked, and he moved down the line without alarm, like a mechanical giant preceded by a sweeping, nervous flow of light. Such he might from the outside have appeared to be, but the man within himself was more like a cat scenting for danger, all muscles and senses delicately tuned to alertness. Door by door, a cautious and thorough inspection; but he found nothing of danger. All the rooms of that wing were used merely for stores and equipment, and they were quite silent and deserted. When he came at last to its end, Carse knew that the wing was safe.

He paused a minute before the laboratory door. He had expected to find it locked, and that he would have to seek other means of entrance; but it was not. By pushing softly against it, it easily gave inward on silent well-oiled hinges. He entered.

arse found himself in a place of memories, and they were sharp and painful in his brain as he stood there. Here so much had happened: here death, and even more than death, had been, and was, so near!

The high-walled circular room was dimly lit by daylight tubes from above. The damage he, Carse, had wrought when besieged in it, a week before, had all been repaired. The place was deserted—it seemed even desolate—but in Carse's moment of memory it was peopled. There had been the tall, graceful shape in black silk; there the operating table and the frail old man bound on it; there the four other men, white men and gowned in the smocks of surgeons, but whose faces were lifeless and expressionless. Dr. Ku Sui and his four assistant surgeons and his intended victim, Master Scientist Eliot Leithgow....

They were all gone from the room now, but there was in it one thing of life that had been there before. It lay behind the inlaid screen which, standing on roller-legs, lay along the wall at one place. The Hawk did not look behind the screen. He could see under it, to know that no one lurked there. He knew what it was meant to conceal. There his promise lay.

But his promise could not be fulfilled immediately. There were four wings to the building, four doors leading into the laboratory, and he had inspected but one.

An open door to his right revealed a corridor similar to the one he had reconnoitered. He repeated down it his methodical search and found no one. Then he returned to the laboratory.

Surely there were men somewhere! Surely someone was behind one of the two closed doors remaining! Gun and flashlight still at the ready, Carse listened a moment at the nearest one.

Silence. He grasped the knob, turned it and quickly threw the door open. A rapid glance revealed no one. Wary and alert, he passed through, and discovered that in this wing were the personal living quarters of Dr. Ku Sui.

The quarters were divided into five rooms: living room, bedroom, library, dining room and kitchen, and the huge metal figure passed through all five, the cold gray eyes taking in every detail of the comfortable but not luxurious furnishings. There was a great interest to him, but it would have to wait.

He reentered the laboratory and went to the remaining door. Bending his head he again listened. A sound—a faint whisper? He fancied he heard something.

Ready for whatever it was, Carse pulled the door wide. And before him he saw the control room of the asteroid, and the men for whom he had been hunting.

hey were white men. Carse recognized them immediately as the four assistants of Dr. Ku Sui. Once, they had been eminent on Earth, respected doctors of medicine and brain surgery, leaders in their profession: now they were like the mechanicalized coolies. For their brains, too, the Eurasian had altered, divested of all humanity and individuality, so as to utilize unhampered their skill with medicine and scalpel.

They were clad in soft yellow robes and seated at ease at one end of a room crowded with a bewildering profusion of gauges, machines, instruments, screens, wheels, levers, and other nameless controlling devices. They did not show surprise at the huge clumsy figure that stood suddenly before them, a raygun in one hand. Like the coolies, their clean-cut features did not change under emotion. All they did was rise silently, as one, gazing at the adventurer out of blank eyes, saying nothing, and making no other move.

Carse tried simple measures in dealing with them. His voice gentle yet firm, he said:

"You must not try to obstruct me. You have seen me before under unfortunate conditions, yet I want you to know that I am really your friend. I mean you no harm; but you must realize that I have a gun, and believe that I will not hesitate to use it if you resist me. So please do not. I only want you to come with me. Will you?"

They were simple words, and what he asked was simple, but would the meaning reach these violated brains? Or would there instead be the desperate reaction of the coolies, who had tried to kill him? Carse waited with genuine anxiety. It would be hard to shoot them, and he knew he could not shoot to kill.

A moment of indecision—and then with relief he saw all four, with apparent willingness, move forward towards him. He directed them through the laboratory and, without sign of resistance, herded them down the corridor he had first searched to the outside.

he light of Jupiter, flooding undiminished through the dome, dazzled him at first. When he could see clearly, he distinguished the great form that was Friday standing motionless by the small port-lock, and, an equal distance away, moving around one of the out-buildings, another similar figure. He spoke by radio.

"Find any, Ban?"

Cheerful words came humming back.

"Only one coolie, Carse. Had no trouble after I disarmed him. He's now locked inside a room in this building. Safe place for prisoners."

"Good," said Carse. "You can see I've got four men—white men. I believe they're unarmed and quite harmless, but I want you to take them, search them and put them away in that room too."

"Coming!"

The distant form rose lightly, skimmed low over the open area between, and grew into the grinning, freckle-faced Ban Wilson. He bounced down awkwardly, almost losing his balance, then surveyed, wonderingly, the four assistants of Ku Sui.

"By Betelgeuse!" he muttered, "—like robots! Horrible!"

"Yes," said the Hawk shortly. "You had no trouble, eh?"

Ban grinned again. "Nothing to mention. This has been soft, hasn't it?"

"Don't be too optimistic, Ban. All right—when you've put these men in the room, please relieve Friday. Send him to me in the laboratory—he knows where it is—and stand watch yourself. If Ku Sui appears—"

"I'll let you know on the instant!"

Hawk Carse nodded and turned back into the corridor from which he had just come. Now he would fulfil his promise. With no possibility of a surprise attack from anyone within the dome, and Ban Wilson posted against the return of Ku Sui, he could attend unhampered to the vow which had brought him there.

e returned to the central laboratory. Quickly be rolled back the high screen lying across one part of the curved wall and stood looking at what was behind it. The monstrousness of that dead-and-alive mechanism overwhelmed his thoughts again.

Before him stood a case, transparent, hard and crystal-like, as long as a man's body and half as deep, standing level on short metal legs. What it contained was the most jealously guarded, the most precious of all Dr. Ku Sui's works, the very consummation of his mighty genius, his treasure-house of wisdom as profound as man then could know. And more: it held the consummation of all that was so coldly unhuman in the Eurasian. For there, in that case, he had bound to his will the brains of five of Earth's greatest scientists, and kept them alive, with their whole matured store of knowledge subservient to his need, although their bodies were long since dead and decayed.

For some time the adventurer stood lost in a mood of thoughts and emotions rare to him—until he was startled back into reality by a heavy, clumping noise coming down the corridor through which he had entered. His gun-hand flickered to readiness, but it was only Friday, coming as he had been ordered. Carse greeted the Negro with a nod, and said briefly:

"There's a panel in this room—over there somewhere—you remember—the place through which Ku Sui escaped when we were here before. It's an unknown quantity, so I want you to stand watch by it. Open your face-plate wide, and warn me at the slightest sound or sight of possible danger."

The Negro nodded and moved as silently as was possible in his space-suit to obey. And Carse turned again to the thing to which he had made a promise.

he icy-glittering case was full of a colorless liquid in which were grouped at the bottom, several delicate, colored instruments, all interconnected by a maze of countless spidery silver wires. Sheathes of other wires ran up from the lower devices to the case's main content—five grayish, convoluted mounds that lay in shallow pans—five brutally naked things that were the brains of scientists once honored and eminent on Earth.

Their bodies has long since been cast aside as useless to the ends of Ku Sui, but the priceless brains had been condemned to live on in an unlit, unseeing deathless existence: machines serving the man who had trapped them into life in death. Alive—and with stray memories, which Ku Sui could not banish entirely, of Earth, of love, of the work and the respect that had once been theirs. Alive—with an unnatural and horrible life, without sensation, without hope. Alive—and made to aid with their knowledge the man who had brought them into slavery unspeakable....

Hawk Carse's eyes were frigid gray mists in a graven, expressionless face as he turned to the left of the case and pulled over one of the well-remembered knife switches. A low hum came; a ghost of rosy color diffused through the liquid in the case. The color grew until the whole was glowing jewel-like in the dim-lit laboratory, and the narrow tubes leading into the undersides of the brains were plainly visible. Something within the tubes pulsed at the rate of heart-beats. The stuff of life.

When the color ceased to increase, Carse pulled the second switch, and moved close to the grille inset in a small panel above the case.

Slowly, gently he said into the grille:

"Master Scientist Cram, Professors Estapp and Geinst, Doctors Swanson and Norman—I wish to talk to you. I am Captain Carse, friend of Master Scientist Eliot Leithgow. Some days ago you aided us in our escape from here, and in return I made you a promise. Do you remember?"

There was a pause, a silence so tense it was painful. And then functioned the miracle of Ku Sui's devising. There came from the grille a thin, metallic voice from the living dead.

"I remember you, Captain Carse, and your promise."

voice from living brain cells, through inorganic lungs and throat and tongue! A voice from five brains, speaking, for some obscure reason which even Ku Sui could not explain, in the first person, and setting to mechanical words the living, pulsing thoughts that sped back and forth inside the case and were coordinated into unity by the master brain, which had once been in the body of Master Scientist Cram. A voice out of nothingness; a voice from what seemed so clearly to be the dead. To Hawk Carse, man of action, it was unearthly; it was a miracle the fact of which he could not question, but which he could not hope to understand. And well might it have been unearthly to anyone. Even to-day.

Still thrilling to the wonder of it, he went on:

"I have returned here to the asteroid with friends. Primarily I came to keep my promise to you, but I intend to do more. Dr. Ku Sui is not here now, and will not be for at least fifteen minutes; but when he does return, I am going to capture him. I am going to take him alive."

He was silent for a moment.

"Perhaps you do not know," he continued levelly, "but the people of Earth hold Master Scientist Eliot Leithgow responsible for your disappearance. He is therefore a fugitive, and there is a price on his head. It is my purpose to restore Eliot Leithgow to his old place by returning Dr. Ku to Earth to answer for the crimes he has effected on you.

"I am now ready to fulfil my promise to you. I expect no interruption this time. I regret exceedingly my inability to destroy you when I was here before, but I simply could not in the little time I had. I still do not know how best to go about it. Perhaps you will tell me. I will wait...."

An afterthought came to him. He added into the grille:

"There is no hurry. Your extraordinary position—your thoughts—I understand...."

Then there was a long silence. For once the Hawk was not impatient; in fact there was in him the feeling that the pause was only decent and fitting. For before him were the brains of five great scientists, who as captive remnants of men had asked him to end their cold and lonely bondage. Limbless, his was to be the hand of their self-immolation. The present silent, slow-passing minutes were to be their last of consciousness....

And then at last spoke the voice:

"Captain Carse, I do not wish you to destroy me. I wish you to give me new life. I wish you to transplant me within the bodies of five living men."

he words, so unexpected, took Hawk Carse by perhaps the greatest surprise he had ever known. For a time he was completely astounded; he could hardly credit his ears. It required a full minute for him to summon even the most halting reply.

"But—but could that be done?" He strove to collect himself, to consider logically this course that he had never dreamed would be requested. "Who could do it? I know of no man."

"Dr. Ku Sui could transplant me."

"Ku Sui? He could, but he wouldn't. He would destroy you, rather."

Almost immediately the artificial voice responded:

"You have said, Captain Carse, that you will soon have Ku Sui captive. Will you not attempt to force him to do as I desire?"

Carse considered the suggestion, but it did not seem remotely possible. Ku Sui could not be prevented from having endless opportunities for destroying the brains while enjoying the manual freedom necessary to perform the operations of re-embodying them.

"I do not see how," he began—and then he cut off his words abruptly.

Something had come into his mind, a memory of something Eliot Leithgow had told him once, long before. Slowly the details came back in full, and at their remembrance his right hand rose to the odd bangs of flaxen hair concealing his forehead and began to smooth them, and a ghost of a smile appeared on his thin lips.

"Perhaps," he murmured. "I think ... perhaps...."

He said decisively into the grille:

"Yes! I think it's quite possible that I can force Ku Sui to transplant you into living bodies! I think—I think—I cannot be sure—that it can be done. At least I will make a very good attempt."

The toneless, mechanical voice uttered:

"Captain Carse, you bring me hope. My thoughts are many, and they are grateful."

But the Hawk had made a promise, and had to be formally freed of the duty it entailed.

"You release me, then," he asked, "from my original promise to destroy you?"

"I release you, Captain Carse. And again I thank you."

The adventurer returned the switches motivating the case, and the faint smile returned to his lips at the thought that had come to him.

But the smile vanished suddenly at the quick, excited words that came crackling into his helmet receiver.

"Carse? Carse? Do you hear me?"

He threw over his microphone control.

"Yes, Ban? What is it?"

"Come as fast as you can. Just caught sight of three distant figures flying straight towards here. It's Ku Sui, returning!"