after you!"
The tunnels, ancient blowholes for the volcanic gases that had torturedMercury with the raising of the titanic mountains, sprawled in alabyrinthine network through those same vast peaks. Only the gallerieslying next the valleys had been explored. Man's habitation on Mercuryhad 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 adesperate chance. But the way back was closed--and he was used to takingchances.
The geography of the district was clear in his mind--the valley he hadjust left and the main valley, forming an obtuse angle with the apex outon the wind-torn plain and a double range of mountains lying out betweenthe sides of the triangle.
Somewhere there was a passage through those peaks. Somewhere there was alanding place, and ten to one there was a ship on it. Caron would neverhave left his men stranded, on the off chance that they might bediscovered and used in evidence against him.
The men now hunting him knew their way through the tunnels, probablywith the aid of markings that fluoresced under infra-red light. Theywere going to take him through, too.
They were coming closer. He waited far up in the main gallery, in themouth of a side tunnel. Now, behind them, he could hear Dio's men. Thenoise 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 metalequipment. 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 voicegrimly. "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'shunt was growing--there must be a good many of them.
Covered by their own echoes, he stole up on the men ahead. His gropinghand 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 agood-sized rock, struck down behind the ear. Gray eased the body downwith scarcely a sound.
Their uniforms, he had noticed, were not too different from his prisongarb. In a second he had stripped goggles, cap, and gun-belt from thebody, and was striding after the others.
They moved like five eerie shadows now, in the queer light of theleader's lamp. Small fluorescent markings guided them. The last mangrunted over his shoulder,
"What happened to you?"
"Stumbled," whispered Gray tersely, keeping his head down. A whisper isa 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 Projectbunch--they'll be using ordinary light. And be quiet!"
They went, through connecting passages. The noise of Dio's party grewominously 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 ofrelief, remembering the body he'd left in the open. For a time the noiseof their pursuers grew remote. And then, suddenly, there was an echoingclamor of footsteps, and the glare of torches on the wall of across-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 toget too far into this maze."
Caron's leader blasphemed softly and dodged into a side tunnel. The mannext to Gray stumbled and cried out with pain as he struck the wall, anda shout rose behind them.
The leader broke into a run, twisting, turning, diving into the maze ofsmaller tunnels. The sounds of pursuit faded, were lost in the tomblikesilence of the caves. One of the men laughed.
"We sure lost 'em!"
"Yeah," said the leader. "We lost 'em, all right." Gray caught the noteof panic in his voice. "We lost the markers, too."
"You mean...?"
"Yeah. Turning off like that did it. Unless we can find that markedtunnel, we're sunk!"
Gray, silent in the shadows, laughed a bitter, ironic laugh.
* * * * *
They went on, stumbling down endless black halls, losing all track ofbranching 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 asubway tube straight to left and right. A wind tore down it, hot as adraught 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. AndGray began to notice a peculiar thing.
The air was charged with electricity. His clothing stiffened andcrackled. His hair crawled on his head. He could see the faintdischarges of sparks from his companions.
Whether it was the effect of the charged air, or the reaction from thenervous strain of the past hours, Mel Gray began to be afraid.
Weary to exhaustion, they struggled on against the burning wind. Andthen they blundered out into a cave, huge as a cathedral, lighted by aqueer, uncertain bluish light.
Gray caught the sharp smell of ozone. His whole body was tingling withelectric tension. The bluish light seemed to be in indeterminate lumpsscattered over the rocky floor. The rush of the wind under thattremendous vault was terrifying.
They stopped, Gray keeping to the background. Now was the time to evadehis unconscious helpers. The moment they reached daylight, he'd bediscovered.
Soft-footed as a cat, he was already hidden among the heavy shadows ofthe fluted walls when, he heard the voices.
They came from off to the right, a confused shout of men under fearfulstrain, growing louder and louder, underscored with the tramp offootsteps. Lights blazed suddenly in the cathedral dark, and from themouth of a great tunnel some hundred yards away, the men of the Projectpoured 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 therock, his flesh blackened jelly, with a rope of glowing light runningfrom 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 ofmotion grew. The scattered lumps melted and flowed together, convergingin 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 allelectricity, 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 dangerof lightning, and his boots were made of rubber, so he felt reasonablysafe, but a tense fear ran in prickling waves across his skin.
Guns began to bark, their feeble thunder all but drowned in the vastrush of the wind. Bullets struck the oncoming waves of light with nomore 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 evenhe couldn't understand, he ran for Jill Moulton.
The first ripples of blue fire touched the ranks of Dio's men. Bolts ofit leaped upward to fasten upon
gun-butts and the buckles of thecartridge belts. Men screamed, fell, and died.
An arm of the fire licked out, driving in behind Dio and the girl. Theguns of Caron's four remaining men were silent, now.
Gray leaped over that hissing electric surf, running toward Jill. Ahungry worm of light reared up, searching for Dio's gun. Gray's handswept it down, to be instantly buried in a mass of glowing ropes. Dio'shatchet face snarled at him in startled anger.
Jill cried out as Gray tore the silver ornaments from her dress. "Throwdown 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 immediatefear spoiled both aim and attention.
Gray caught up Jill and began to run, toward the tube from which thewind howled in the cave. Behind