Julia stumbled in retreat, her mouth falling open in horror. The Chittrix rose smoothly, driven from the water by its immense hindquarters and spiked tail.

Fox remained oblivious, his back to the river.

The base of Julia’s spine collided with a sharp metal edge, and her belly became loose and liquid as the Chittrix nightmare sliced through the damp air toward them. Her mouth opened, but there was no air in her lungs to scream.

Sawyer clocked her expression. His head twisted and realization flashed across his face as he raised his weapon simultaneously.

The Chittrix arced across the vaulted ceiling, slivery-grey in the strobing light, an alien shark diving effortlessly fifteen feet above their heads. Water sluiced in silver sheets from the barbed spine and scaled, black body.

Sawyer fired several quick bursts with his pulse rifle then grabbed Julia roughly by her upper arm, forcing her frozen feet into motion. She stumbled after him but terror made her feet clumsy and she sprawled headlong, her hands jarring painfully on the cold floor.

Fox ducked in response to the shots. One hand flew up to protect his skull as he dropped to his knees, the other fumbled for the weapon holstered at his hip.

Violet spun on her heel, raising her MP5 in tandem with Garrick and Hardy, the snub-noses of their weapons directed at the barbed invader. Her fingers squeezed the trigger, unleashing a deadly spray at the Chittrix.

Julia screamed now, her voice drowned out in the violent weapon-fire. She staggered onto to her feet, but before she could run, Sawyer shoved her across the gritty floor toward the far wall, stepping between her and the Chittrix. Julia’s face collided with concrete cheek first, her teeth snapping in her mouth and piercing her tongue, releasing a hot, coppery bloom. She scrabbled to turn, compelled to watch the nightmare unfolding behind her.

It had come from the river. The river that supplied the base via miles of underground channels.

The Chittrix landed on the concrete floor of the plant room, the impact vibration burrowing under Julia’s skin. Its clawed hind legs scraped for purchase as elongated pincers on its forelimbs stretched for the closest human.

Fox crawled, his legs slipping in a frenzied panic. His hands clawed at the floor as he tried desperately to pull himself away from the alien nightmare.

He wasn’t fast enough.

One bulbous, clubbed-front mandible hit him, crashing into his side as he dragged himself to his feet. Fox contorted, his feet leaving the ground as he was thrown through the air, one shoe lost. He hit the rock wall of the cavern ten feet above the ground, his body crumpling against the cragged surface before dropping in a bloody pile.

Julia watched, horrified, terror overwhelming her as everything seemed to unfold in slow motion. The Chittrix screamed triumphantly, rearing on its hindquarters over Fox’s inert form. Ammunition riddled its abdomen and thorax but the Chittrix was defiant and its head whipped violently, evading the onslaught of fire.

Its tail lashed forward in a bone-crushing sweep, knocking Sawyer and Violet flat. Sawyer brought his weapon up with barely a pause but Violet lay motionless for a second. Then she rolled onto her front, pulling her hands under her body and crawled to her hands and knees. Julia sucked in a hitching gasp of relief.

The Chittrix lunged. It bellowed, elongating its neck and baring shards of glinting teeth that crisscrossed each other in a hellish jumble.

Julia recoiled from the battle cry as she finally made it back onto her feet. Her attention was drawn to the rear of the cavern by a pregnant swelling in the river. As she watched, the water rose and split in a slash of grey bubbles as a second Chittrix emerged.

Fuck.

Finally, her brain overrode her paralysis, and she sprinted across the open floor to the pile of man that was Fox.

Garrick, Foster, Hardy, and Violet now surrounded the first Chittrix. The four of them danced in and out of its grasp, taunting it with bullets as Garrick’s machete sliced noisily through exposed gaps in the alien armor. Sawyer bellowed and ran to the edge of the water, his gun aimed at the second Chittrix swimming with powerful strokes toward him.

Julia slid to her knees in front of Fox, jagged grit cutting into her flesh. He lay facing the wall, and warm blood soaked her shins instantly. She placed two fingers on his neck; a thready pulse skittered under her fingertips. He was still alive. She leaned over him, checking his airway was clear, then heaved him into the recovery position. One hand flopped uselessly against the concrete while his other twisted from the elbow at an unnatural angle.

The screams behind Julia grew louder, a cacophony of brutal threats from the Chittrix as it bobbed and weaved, and the battle cries of the human fighters who rallied against it. The brutality filled her ears against her will.

She wanted to press her palms to her skull to block out the sounds, but her hands found the wet mess of Fox’s abdomen instead. He was bleeding out. She tore her cotton t-shirt over her head, the water-chilled air pebbling her skin. Shivering in her bra, she balled the t-shirt into a tight wad then pressed it against the exposed, wet sloppiness of his wound. She wanted to scream for a doctor, but there was no point, every other pair of hands held a weapon directed at the Chittrix. Julia huddled protectively over him. She’d never liked him much, but kneeling here in his blood, she was confronted with his humanity, the slender thread they shared against the Chittrix. She spoke in his ear, whispering that he was going to be okay. His eyelids fluttered, but it was impossible to tell if he was conscious.

She risked a glance over her shoulder. Foster and Garrick were slick with yellow Chittrix fluid. Garrick danced close with his machete while Foster unleashed more bullets into the underside of the Chittrix’s skull. It howled and lashed out. Stubby claws hit Foster on the temple and hurled him to the ground.

“Sawyer!” Julia cried.

He was on his hands and knees, close to the barrier that separated the basement from the dark void of water below. He ripped a cable from the bank of computers near the water’s edge. While he struggled and cursed in the blinking light, Violet distracted the Chittrix in the water. It surged repeatedly for the edge of the platform, but Violet was ready every time, with a storm of fire that kept it gaining purchase on the platform. It hissed with frustration, churning the water to foam.

Sawyer staggered across the concrete to join Violet, hauling the now-disengaged cable with him. Violet stepped back, and he lunged forward, flinging the cable into the water where it connected with the surface in a deafening crack.

All hell broke loose.

The Chittrix in the water arched backward with a throttled howl. Julia recoiled, her shoulders rising in a futile attempt to protect her ears as she staunched the flow of blood from Fox’s torn body.

The first Chittrix spasmed at the cry of its companion, its head snapping round with whip-crack speed to the seething water.

Sawyer dove on top of Violet, shielding her body.

Finally, the power shorted out with a splintering boom and the second Chittrix crashed under the water, a huge tidal wash of grey foam covering its dying form. Sparks flew across the surface in arcs of blue and yellow light, then one of the computer control panels exploded, filling the air with projectile missiles of hot plastic and metal shards. Smoke obscured the air, rich with the stench of burning meat.

The first Chittrix spun and howled, teeth bared in fury. It leaped toward Violet and Sawyer but hurtled over them, its injured body twitching as it barreled through the air toward the river.

It shrieked as it hit the boiling water, plunging under the surface in one sleek motion and driving past the floating corpse of its companion. With a final snap of its tail, the Chittrix was gone.