Doom Helix. James Axler

legs, torso and head banged around inside it. The intelligent armor fit the others like a second skin, but they were Level Four, genetically enhanced females, the ultimate warriors of his native Earth. As a relatively uncoordinated Homo sapien male, Dr. Huth could only utilize a few of the battlesuit’s basic functions. And it wasn’t just a matter of body size and strength differential; his unmodified nerves and synapses couldn’t fully interface with the suit’s controls or handle the speed and volume of data transfer.

      The sterilization unit was a ten-foot-long section of corrugated cylinder laying on its side, tall enough and wide enough to admit a single warrior dressed in full battle gear. Decontamination had been part of their pre-jump regimen ever since Shadow World, the first parallel Earth targeted for conquest.

      Unlike their own exhausted and dying home, Shadow World had had bountiful, untapped natural resources on land and sea, and a relatively tiny, technologically stagnant human population that was easily subdued. But before the invaders could gain a foothold, infection by an indigenous lethal microbe forced them to make a hasty exit to another parallel Earth. Dr. Huth had solved the immediate crisis by killing the bacteria with bursts of X-ray radiation, but the replica Earth on which they had rematerialized was long dead and worthless to them. So, they had had no choice but to jump again.

      And again.

      And again.

      And again.

      World after human-occupied world they found either already destroyed and uninhabitable, or in the midst of annihilation. The Apocalyptic scenario that had driven Dr. Huth and the warriors from their home Earth replayed over and over in parallel dimensions—the same horrendous outcome, only with different chains of causation. For one reason or another, in every version of reality that they visited, humankind and its birth planet were doomed.

      Then, finally, on the tenth replica of Earth had come a glint of hope.

      Like their native world, it had a vast human population, but ninety per cent of it was well past reproductive age and rapidly approaching maximum lifespan, with accompanying mental and physical diminution. The machinery of its global society still functioned, extracting and transporting still-plentiful resources, but just barely. It was a wrinkled, limping planet. An overripe plum ready to pluck.

      Dr. Huth had been confident that they would be the ones doing the plucking.

      But he was wrong.

      The scourge had appeared a few weeks after their arrival, after they had seized the reins of power, but long before their advanced genetic and weapons technologies could give them full control over a weakened and stunned populace. It was unlike anything the planet had ever endured, unlike anything the whitecoat Dr. Huth had even dreamed possible. And as it spread unchecked, crossing oceans, continents, ice caps with stunning speed, the evidence that he and the other reality-jumpers had brought it with them steadily mounted—until it was indisputable.

      As fate would have it, the seed of the Apocalypse lay scattered not only upon the seemingly infinite copies of Earth, but also across the True Void, the transitional Nothingness, the Null space between universes. And Dr. Huth and his fellow invaders, the would-be conquerors of a hundred parallel worlds, had inadvertently picked up and transported those seeds, that unspeakable contamination, to the first planet that could have sustained them, and which would have served as a launching pad for all their ambitions.

      Once the scourge took hold on the tenth Earth, the only defense against it had been force field and battlesuit. There was nowhere else safe to run, nowhere safe to hide, and no way to fight back. Weapons of war intended for intrareality combat—even the warriors’ tribarreled laser rifles—had done nothing to slow the mass extermination of the planet’s most complex organisms. It wasn’t just humans who died—no higher animals were spared, cold- or warm-blooded, large or small. Dr. Huth’s mathematical models had forecast a bleak future: When the cycle of slaughter finally ended, only the planet’s multicellular plant species and the prokaryotes would be left alive.

      The evolutionary clock was running backward.

      To escape the global disaster they had set in motion, the reality-travelers had jumped again.

      Dr. Huth reached out a black-gauntleted hand and threw back the door flap of the sterilization chamber. He braced himself on the plast-steel frames that held the banks of X-ray generators and stepped onto the low, gridwork target pedestal. The beams were angled to cover every square inch of the suit, even the soles of his boots. He had ramped up the X-ray intensity, hoping that the application of maximum available power would resolve their predicament.

      Toeing the marker on the pedestal, he hit the power switch, raised his arms over his head and spread his gauntleted fingers. The battlesuit visor reacted infinitely faster than eyes and brain. Before the latter could even begin to register the blast of energy, the helmet’s autosensors opaqued the lens to petroleum-black.

      The X-ray pulse lasted one minute, and in theory at least, blasted the suit’s external surfaces clean of all living matter. If it worked, they would depart this replica Earth without scourge stowaways.

      After his visor cleared, Dr. Huth exited the tunnel’s rear and passed through to a second force field—the smaller dome-within-a-dome that enclosed the jump zone. Before him, similarly clad in segmented, gleaming black battlesuits, a dozen surviving warriors set the stage for departure. They were triaging out the most vital gear—weapons, food and medical stores, and scientific apparatus. Behind them stood the mobile, nuke-ore processor, three transport vehicles and a single gyroplane. The rest of their matériel had to be abandoned; the smaller the payload, the less power the jump required.

      Beyond the nested containment fields, a pitched, one-sided battle raged. Without the battlesuits’ optical enhancements, the seemingly endless legions of attackers were invisible. All that could be seen of them with the naked eye were the corkscrewing aerial wakes they left when passing through smoke or fog or rain—and perhaps that was a blessing in disguise. In his helmet’s viewscreen they flew, they floated, they slithered, they massed in thin air like the glowing ghosts of six-foot-long slime eels. The specterlike entities seemed unaffected by planetary gravity, a phenomenon that sorely baffled Dr. Huth. It appeared that although they existed in the current dimension, wreaking havoc as they swarmed and killed, they were somehow not fully of it.

      Great luminous blotches of color splashed high on the flanks of the outermost containment dome. Liquid dripped down the impenetrable curtain in rivulets of brilliant lime green.

      Hot blood, as seen in infrared.

      The gouts of gore splattered the surface of the force field, hung there for an instant, then were gone, vaporized as the barrier shrugged off the insult.

      Similar slaughter was raining down upon the planet’s entire surface, upon living creatures even less prepared to defend themselves.

      Megadeath.

      It had followed their leap from the tenth Earth to the eleventh, and now from the eleventh to the twelfth, seemingly homing on the chemistry of their blood and marrow, using them not only for transport, but also as guides to suitable targets, to like-worlds prime for annihilation.

      Working frantically in the 18-to-21-day windows of calm between rematerialization and all hell breaking loose, Dr. Huth had gathered a scant handful of facts. It appeared that the creatures first entered the bodies of their hosts as microscopic entities, drawn into the lungs with breath, into the stomach with food and water, and into the soft tissue through breaks in the skin. Like bacterial endospores, their incredibly tough, shell-like outer covering protected them from the hazards of deep space and presumably, those of the True Void. Like endospores, these entities had a lethality threshold.

      Under strictly controlled laboratory conditions, he had destroyed them with direct heat in excess of 2000 degrees Fahrenheit, and with maximum-power X-ray exposure. The direct heat method was not applicable in the real world; those temperatures would have flash-cooked the warriors in their battlesuits. Whether the X-ray radiation level and coverage in the sterilization chamber was sufficient to cleanse them of all microscopic contamination was an open question.

      Even