Gray was up and running again. He knew the way into the explored galleries. From there on, it was anybody's guess.
Caron was brazen enough about it. The subtle way had failed. Now he was going all out. And he was really quite safe. With the broken cables to act as conductors, the first thunderstorm would obliterate all proof of his activities in this valley. Mercury, because of its high electrical potential, was cut off from communication with other worlds. Moulton, even if he had knowledge of what went on, could not send for help.
Gray wondered briefly what Caron intended to do in case he, Gray, made good his escape. That outpost in the main valley, for which Ward had been heading, wasn't kept for fun. Besides, Caron was too smart to have only one string to his bow.
Shouts, the spatter of shots around them. The narrow trail loomed above. Gray sent the girl scrambling up.
The sun burst up over the high peaks, leaving the black shadow of the valley still untouched. Caron's ship roared off. But six of its crew came after Gray and Jill Moulton.
The chill dark of the tunnel mouth swallowed them. Keeping right to avoid the great copper posts that held the cables, strung through holes drilled in the solid rock of the gallery's outer wall, Gray urged the girl along.
The cleft his hand was searching for opened. Drawing the girl inside, around a jutting shoulder, he stopped, listening.
Footsteps echoed outside, grew louder, swept by. There was no light. But the steps were too sure to have been made in the dark.
"Infra-red torches and goggles," Gray said tersely, "You see, but your quarry doesn't. Useful gadget. Come on."
"But where? What are you going to do?"
"Escape, girl. Remember? They smashed my ship. But there must be another one on Mercury. I'm going to find it."
"I don't understand."
"You probably never will. Here's where I leave you. That Martian Galahad will be along any minute. He'll take you home."
Her voice came soft and puzzled through the dark.
"I don't understand you, Gray. You wouldn't risk my life. Yet you're turning me loose, knowing that I might save you, knowing that I'll hunt you down if I can. I thought you were a hardened cynic."
"What makes you think I'm not?"
"If you were, you'd have kicked me out the waste tubs of the ship and gone on. You'd never have turned back."
"I told you," he said roughly, "I don't kill women." He turned away, but her harsh chuckle followed him.
"You're a fool, Gray. You've lost truth--and you aren't even true to your lie."
He paused, in swift anger. Voices the sound of running men, came up from the path. He broke into a silent run, following the dying echoes of Caron's men.
"Run, Gray!" cried Jill. "Because we're coming after you!"
The tunnels, ancient blowholes for the volcanic gases that had tortured Mercury with the raising of the titanic mountains, sprawled in a labyrinthine network through those same vast peaks. Only the galleries lying next the valleys had been explored. Man's habitation on Mercury had been too short.
Gray could hear Caron's men circling about through connecting tunnels, searching. It proved what he had already guessed. He was taking a desperate chance. But the way back was closed--and he was used to taking chances.
The geography of the district was clear in his mind--the valley he had just left and the main valley, forming an obtuse angle with the apex out on the wind-torn plain and a double range of mountains lying out between the sides of the triangle.
Somewhere there was a passage through those peaks. Somewhere there was a landing place, and ten to one there was a ship on it. Caron would never have left his men stranded, on the off chance that they might be discovered and used in evidence against him.
The men now hunting him knew their way through the tunnels, probably with the aid of markings that fluoresced under infra-red light. They were going to take him through, too.
They were coming closer. He waited far up in the main gallery, in the mouth of a side tunnel. Now, behind them, he could hear Dio's men. The noise of Caron's outfit stopped, then began again, softly.
Gray smiled, his sense of humor pleased. He tensed, waiting.
The rustle of cloth, the furtive creak of leather, the clink of metal equipment. Heavy breathing. Somebody whispered, "Who the hell's that back there?"
"Must be men from the Project. We'd better hurry."
"We've got to find that damned Gray first," snapped the first voice grimly. "Caron'll burn us if we don't."
Gray counted six separate footsteps, trying to allow for the echoes. When he was sure the last man was by, he stepped out. The noise of Dio's hunt was growing--there must be a good many of them.
Covered by their own echoes, he stole up on the men ahead. His groping hand brushed gently against the clothing of the last man in the group. Gauging his distance swiftly, he went into action.
One hand fastened over the fellow's mouth. The other, holding a good-sized rock, struck down behind the ear. Gray eased the body down with scarcely a sound.
Their uniforms, he had noticed, were not too different from his prison garb. In a second he had stripped goggles, cap, and gun-belt from the body, and was striding after the others.
They moved like five eerie shadows now, in the queer light of the leader's lamp. Small fluorescent markings guided them. The last man grunted over his shoulder, "What happened to you?"
"Stumbled," whispered Gray tersely, keeping his head down. A whisper is a good disguise for the voice. The other nodded.
"Don't straggle. No fun, getting lost in here."
The leader broke in. "We'll circle again. Be careful of that Project bunch--they'll be using ordinary light. And be quiet!"
They went, through connecting passages. The noise of Dio's party grew ominously loud. Abruptly, the leader swore.
"Caron or no Caron, he's gone. And we'd better go, too."
He turned off, down a different tunnel, and Gray heaved a sigh of relief, remembering the body he'd left in the open. For a time the noise of their pursuers grew remote. And then, suddenly, there was an echoing clamor of footsteps, and the glare of torches on the wall of a cross-passage ahead.
Voices came to Gray, distorted by the rock vaults.
"I'm sure I heard them, just then." It was Jill's voice.
"Yeah." That was Dio. "The trouble is, where?"
The footsteps halted. Then, "Let's try this passage. We don't want to get too far into this maze."
Caron's leader blasphemed softly and dodged into a side tunnel. The man next to Gray stumbled and cried out with pain as he struck the wall, and a shout rose behind them.
The leader broke into a run, twisting, turning, diving into the maze of smaller tunnels. The sounds of pursuit faded, were lost in the tomblike silence of the caves. One of the men laughed.
"We sure lost 'em!"
"Yeah," said the leader. "We lost 'em, all right." Gray caught the note of panic in his voice. "We lost the markers, too."
"You mean...?"
"Yeah. Turning off like that did it. Unless we can find that marked tunnel, we're sunk!"
Gray, silent in the shadows, laughed a bitter, ironic laugh.
They went on, stumbling down endless black halls, losing all track of branching corridors, straining to catch the first glint of saving light. Once or twice they caught the echoes of Dio's party, and knew that they, too, were lost and wandering.
Then, quite suddenly, they came out into a vast gallery, running like a subway tube straight to left and right. A wind tore down it, hot as a draught from the burning gates of Hell.
It was a moment before anyone grasped the significance of that wind. Then someone shouted, "We're saved! All we have to do is walk against it!"
They turned left, almost running in the teeth of that searing blast. And Gray began to notice a peculiar thing.
The air was charged with electricity. His clothing stiffened and crackled. His hair crawled on his head. He could see the faint discharges of sparks from his companions.
Whether it was the effect of the charged air, or the reaction from the nervous strain of the past hours, Mel Gray began to be afraid.
Weary to exhaustion, they struggled on against the burning wind. And then they blundered out into a cave, huge as a cathedral, lighted by a queer, uncertain bluish light.
Gray caught the sharp smell of ozone. His whole body was tingling with electric tension. The bluish light seemed to be in indeterminate lumps scattered over the rocky floor. The rush of the wind under that tremendous vault was terrifying.
They stopped, Gray keeping to the background. Now was the time to evade his unconscious helpers. The moment they reached daylight, he'd be discovered.
Soft-footed as a cat, he was already hidden among the heavy shadows of the fluted walls when, he heard the voices.
They came from off to the right, a confused shout of men under fearful strain, growing louder and louder, underscored with the tramp of footsteps. Lights blazed suddenly in the cathedral dark, and from the mouth of a great tunnel some hundred yards away, the men of the Project poured into the cave.
And then, sharp and high and unexpected, a man screamed.
The lumps of blue light were moving. And a man had died. He lay on the rock, his flesh blackened jelly, with a rope of glowing light running from the metal of his gun butt to the metal buttons on his cap.
All across the vast floor of that cavern the slow, eerie ripple of motion grew. The scattered lumps melted and flowed together, converging in wavelets of blue flame upon the men.
The answer came to Gray. Those things were some form of energy-life, born of the tremendous electric tensions on Mercury. Like all electricity, they were attracted to metal.
In a sudden frenzy of motion, he ripped off his metal-framed goggles, his cap and gun-belt. The Moultons forbade metal because of the danger of lightning, and his boots were made of rubber, so he felt reasonably safe, but a tense fear ran in prickling waves across his skin.
Guns began to bark, their feeble thunder all but drowned in the vast rush of the wind. Bullets struck the oncoming waves of light with no more effect than the eruption of a shower of sparks. Gray's attention, somehow, was riveted on Jill, standing with Dio at the head of her men.
She wore ordinary light slippers, having been dressed only for indoors. And there were silver ornaments at waist and throat.
He might have escaped, then, quite unnoticed. Instead, for a reason even he couldn't understand, he ran for Jill Moulton.
The first ripples of blue fire touched the ranks of Dio's men. Bolts of it leaped upward to fasten upon gun-butts and the buckles of the cartridge belts. Men screamed, fell, and died.
An arm of the fire licked out, driving in behind Dio and the girl. The guns of Caron's four remaining men were silent, now.
Gray leaped over that hissing electric surf, running toward Jill. A hungry worm of light reared up, searching for Dio's gun. Gray's hand swept it down, to be instantly buried in a mass of glowing ropes. Dio's hatchet face snarled at him in startled anger.
Jill cried out as Gray tore the silver ornaments from her dress. "Throw down the guns!" he yelled. "It's metal they want!"
He heard his name shouted by men torn momentarily from their own terror. Dio cried, "Shoot him!" A few bullets whined past, but their immediate fear spoiled both aim and attention.
Gray caught up Jill and began to run, toward the tube from which the wind howled in the cave. Behind him, grimly, Dio followed.
The electric beasts didn't notice him. His insulated feet trampled through them, buried to the ankle in living flame, feeling queer tenuous bodies break and reform.
The wind met them like a physical barrier at the tunnel mouth. Gray put Jill down. The wind strangled him. He tore off his coat and wrapped it over the girl's head, using his shirt over his own. Jill, her black curls whipped straight, tried to fight back past him, and he saw Dio coming, bent double against the wind.
He saw something else. Something that made him grab Jill and point, his flesh crawling with swift, cold dread.
The electric beasts had finished their pleasure. The dead were cinders on the rock. The living had run back into the tunnels. And now the blue sea of fire was flowing again, straight toward the place where they stood.
It was flowing fast, and Gray sensed an urgency, an impersonal haste, as though a command had been laid upon those living ropes of flame.
The first dim rumble of thunder rolled down the wind. Gripping Jill, Gray turned up the tunnel.
The wind, compressed in that narrow throat of rock, beat them blind and breathless, beat them to their bellies, to crawl. How long it took them, they never knew.
But Gray caught glimpses of Dio the Martian crawling behind them, and behind him again, the relentless flow of the fire-things.
They floundered out onto a rocky slope, fell away beneath the suck of the wind, and lay still, gasping. It was hot. Thunder crashed abruptly, and lightning flared between the cliffs.
Gray felt a contracting of the heart. There were no cables.
Then he saw it--the small, fast fighter flying below them on a flat plateau. A cave mouth beside it had been closed with a plastic door. The ship was the one that had followed them. He guessed at another one behind the protecting door.
Raking the tumbled blond hair out of his eyes, Gray got up.
Jill was still sitting, her black curls bowed between her hands. There wasn't much time, but Gray yielded to impulse. Pulling her head back by the silken hair, he kissed her.
"If you ever get tired of virtue, sweetheart, look me up." But somehow he wasn't grinning, and he ran down the slope.
He was almost to the open lock of the ship when things began to happen. Dio staggered out of the wind-tunnel and sagged down beside Jill. Then, abruptly, the big door opened.
Five men came out--one in pilot's costume, two in nondescript apparel, one in expensive business clothes, and the fifth in dark prison garb.
Gray recognized the last two. Caron of Mars and the errant Ward.