Momentarily, he thought of Laura and, because it had grown to be synonymous with her, the murder of Big Tim. His mental picture of the girl had never been more beautiful, desirable, or appealing. Every quality which she had ever possessed, real in actuality or imaginary as a result of his idealizations, was now transcended beyond all mortal planes. She became the very embodiment of every human aspiration and desire.

Surely, he found himself reasoning with that curious pleasure and contentment which had come over him, the murder of Big Tim for so glorious and wonderful a girl could be no base act. And the scruples which had forever risen to bar him mockingly from the actual deed, were now so smoothed away that he would never have known he had had them. Big Tim would die, of course. And he would take great pleasure in killing him. There would be no regrets, no self-accusations, no torturing pangs of conscience. There would only be complete satisfaction, comfort, and happiness. And Laura would be his. There was no doubt about that. There was no doubt anywhere in his mind. There was only complete gratification of every whimsical and vagrant thought or desire.

Then a sudden jar shook him. For a moment he had the sensation of struggling up from warm, drowsy depths. And then, suddenly, he was looking into Big Tim Austin's puzzled and incredulous face, and that eery mental surcease was gone.

"Brad--did you feel it, too?"

Nellon nodded wordlessly. He was a little frightened of the weird force that had held them both in thrall. A glance at the column looming gigantically before him showed that he and Big Tim had walked a good distance without any conscious knowledge of having done so. It was the chance collision which had aroused them both from their sleep-walking state.

Nellon could feel the force yet, brushing at the fringes of his mind with warm, soothing fingers. But he soon found that, with active resistance, there was no fear of it overcoming him again. One thing persisted, however, and that was the curiously refreshed and stimulated condition of his body. Nor was he anxious that this should go away.

They were within yards of the great column, now, and at an ever shortening range their eyes began to make out certain details which they had missed during their progress under that inexplicable half-trance.

It was not actually a column, they realized, for it was hollow and they could dimly make out the shapes of objects within. It was a vast, room-like cylinder or enclosure, with walls of transparent green. In the center, and midway between floor and ceiling, there hung what seemed to be a ball of vivid green fire.

Upon reaching the cylinder, they pressed closely to its hard surface and peered intently within. But at first the great, flaming ball obscured such early details as they could discern. It was like looking upward through water at the blinding disc of the sun. Then, as their eyes grew accustomed to the emerald brilliance, they found themselves gazing at an unbelievable scene.

High above floated the fiery, green ball. Directly below it glittered the complex ma.s.s of a great machine. This was spread upon a huge base and narrowed as it rose. Circling the apex were a mult.i.tude of rod-like projections, the ends of which terminated in large crystal cones. The bases of these were pointed upward, and from each a pale, almost invisible, beam shot up and into the green ball, as though at once nourishing and supporting it.

But it was not this which held the incredulous fixity of their gaze. For arranged in concentric circles about the machine were hundreds of tables or low platforms and upon each a still figure lay. The nearest table was some distance from the wall through which Nellon and Austin peered, and this, added to the weird, green light of the globe, made a clear delineation of physical characteristics impossible. Yet they were able to make out enough to become convinced, that, as their earlier examination of the clothing in the rooms had suggested, the figures were hauntingly human.

For a long moment they stood there. Then Big Tim turned, and Nellon, looking around in response to the action, was amazed at the bright and feverish gleam in the other's eyes. Words tumbled from Big Tim's lips in a hoa.r.s.e rush.

"Brad, this is going to make interplanetary history. It's the biggest thing since the discovery of the first dead city on Mars. We've got to go back to the ship and bring the others. They've got to see this. But, Brad, before they do, I'm going in there. I want to be the first to see what these people looked like. There must be a door somewhere--"

And before Nellon could voice the protest which rose to his lips, Big Tim had started away on an eager circuit of the green wall. Nellon stood looking after him in indecision, torn between conflicting impulses. Then he tightened his lips and followed in the direction which Big Tim had taken. But before Nellon could reach him, the other's excited voice crashed in his earphones.

"I've found it, Brad! There _is_ a door here."

Nellon jerked into a run. He found Big Tim standing upon a short ramp before a section of the wall which was different from the rest. It was a dark area, rectangular in shape. At one side, seen dimly through the strange green substance, was an arrangement of rods and gears which was obviously an operating mechanism. Protruding from a slot in the wall, and clearly connected with the mechanism, was a short lever.

Big Tim's blue eyes glittered with daring. His tow hair awry, he looked more than ever the picture of an overgrown, impulsive boy.

"Good heavens, guy, you surely don't intend to go in there!" Nellon exclaimed. "We don't know what sort of--"

Big Tim gave a short, excited laugh. "Look--there's nothing to be afraid of. There's just that green light up there and the people, and they are dead. Everything in this place is dead. Brad, this is the chance of a lifetime. We'll be the first to look upon the faces of an extra-terrestrial race since the Martians."

Big Tim pulled the opening lever. There was a moment of appalled and complete quiet. Then hidden motors hummed into alien life, and slowly the door before them slid aside. Undimmed now by its confining walls, the green radiance poured through the opening in a blinding flood.

"Come on," Big Tim urged. And without any hesitation on his own part, he stepped through, to be bathed instantly in the emerald glow.

Nellon moved to the open doorway. The emerald rays from the globe fell upon him with an almost sensible warmth. Again that weird peace and comfort was upon him, but more overpoweringly now. He felt a rising tide of drowsiness. In some strange way, he knew it would be good to allow himself to succ.u.mb to the softly-blanketing darkness which was filling his mind. It would be a blessed surcease from all the troubles and cares of his present world. But something held him back.

And though a great, calm voice seemed to give him every a.s.surance of safety, a stubborn, small one screamed him its warning. In a turmoil, he watched Big Tim stride toward the nearest of the platforms.

It became evident to Nellon almost immediately that Big Tim was never going to reach his goal. For shortly after the first several steps, the blonde giant's purposeful walk slowed to a bemused shamble. And, watching with a curiously disembodied attention, Nellon saw him waver, stop, and then collapse upon the floor, as though he had suddenly become very, very tired.

The warning voice was shrieking now. Nellon felt a swift rush of terror that ripped him free of the force which enclosed him in its lulling folds. He shot a wide-eyed glance from the gleaming, inert shape of Big Tim's suit to the globe flaming high above. He wanted suddenly to run.

He struggled in panic against the invisible bonds of peace and comfort which were so reluctant to let him go. His determination to be free was the fierce and frenzied one of utter fear. Flailing his arms as if against some material foe, he managed to stumble down from the ramp, to one side of the doorway where the green light would not reach him.

Exhausted from the herculean struggle, he slumped to the floor. A soft, warm blackness was settling over him, and he was powerless to fend it off. But he knew that he was safe, and the satisfaction which he felt was increased by the radiation which he had absorbed, so that when he finally swooped into unconsciousness, it was amidst a thunderous, victorious singing.

Nellon's next sensations were curious ones. He seemed to awaken in another realm. It was a vast and formless place with no distinguishable feature or color, but it was curiously sentient, pulsing with awesome possibilities.

Now, as though stirred by his reflection upon it, the nebulous stuff began to writhe. And then, taking shape from the formless jumble of thoughts in his subconscious, a dream-world began to grow. Bits were added here, others discarded there, but every compartment in the storehouse of his mind contributed something. And all a.s.sembled in accordance with the pattern Nellon had fashioned in two and a half years of brooding. Finally his dream paradise was complete to the last detail of his hopes and imaginings.

It was the world which he had built around Laura taken on an immaterial, but to him nonetheless real, life. There was Laura and there was himself. And there was the complete bliss for which he had planned Big Tim's murder to achieve.

He became aware of a change. The outlines of his world were dimming, dissolving, fading. Even Laura, radiantly lovely, was beginning to blur before his eyes.

In horror he sought to clutch the evaporating structure to him and stabilize it once again. But it slipped through his fingers like an impalpable mist. Before he was fully alive to it, his dream Eden was gone, and he was back in that formless void in which he had found himself. And even that was thinning.

Nellon awoke. He looked around for Laura and that idyllic dream land in which they had loved. But only the great, green cylinder with its flaming globe and the vast room beyond met his gaze.

Nellon climbed to his feet. With the action, he became aware that he felt wonderfully refreshed and stimulated. He looked around for Big Tim, then he remembered. Avoiding the open doorway through which the rays still poured, he peered through the green wall. Big Tim was lying there on the floor within. He was very still in his thermalloy suit.

Nellon began a chain of reasoning. As it progressed, there went with it a rising tide of exultation.

As long as Big Tim remained there under the influence of the globe, he would remain unconscious, living, perhaps, a dream as real and vivid as his own had been. It would be just as though Big Tim were dead. None of the expedition members knew of the doorway through which he and Big Tim had entered. With the almost continuous storms which raged on t.i.tan, the door would soon become covered again. Ages might pa.s.s before a chance accident revealed it once more.

He, Nellon, could go back to the ship with a tale of how he had lost Big Tim in the bitter storm. The men might search, but he knew it would be futile.

Laura would grieve, of course, when he returned and told her the news.

But he would be there to comfort her, and she would get over it. And he knew that she would marry him, with Big Tim out of the way. He could look forward to a happiness more satisfying than that of the dream.

Nellon saw his course clear. He knew just what he had to do.

First he released the lever, and the door slid shut, entombing Big Tim within the great cylinder. Then he retraced his way down to the lower level and through the maze of rooms and corridors. It was not long before the snow of t.i.tan once more keened against his suit.

He threw his weight against the great door. Only the impulse was necessary to close it, for the operating mechanism hummed into vibrant life and it swung shut where it had not been shut before--and locked!

Nor would it open again.

Even if he had wanted to re-enter, that was impossible.

Nellon started back to the ship. With the curious vigor he felt, the dangers and difficulties of the return trip hardly registered upon him at all. Gone was his sullen dislike of the ever-raging storm. He plowed through it with a careless smile, fighting his way over the wild and tumbled terrain. And it was with no feeling of exhaustion at all that he finally sighted the great, toothed ice ridge which marked the site of the camp.

As Nellon shouldered through the narrow cleft which led into the protected, tiny valley, he remembered to remove the smile of eager triumph upon his face. It would not go with the story he was to tell.