Chapter 8:
Serum Trials
The tunnel swallowed us whole, its gaping maw sealing shut behind us with a finality that made my skin crawl. The darkness wasn't just absence of light. It was a living thing, thick and viscous, pressing against my eyeballs until phantom shapes danced at the edges of my vision. Nia's flashlight beam cut through the gloom like a dying star, its weak yellow light catching on the moisture beading along the curved concrete walls. The air tasted of wet earth and something metallic, like licking a battery, and every inhale carried the scent of decades-old decay from things better left buried.
My ribs ached where Sarin's fingers had dug in, each breath sending fresh pulses of pain radiating through my torso. The echoes of our footsteps overlapped in the narrow space, creating a disorienting chorus that made it sound like we were being followed by ghosts. When I glanced back, Sarin's silhouette moved with predatory grace, his pistol a dark extension of his arm. His eyes caught the light like a cat's, two chips of reflected amber that never stopped scanning, assessing, watching Nia with growing suspicion.
Nia moved like a marionette with its strings half-cut. Her usual fluidity had been replaced by jerky, overcompensating motions, her shoulders hitching with each step as if fighting some invisible current. Every few paces she'd whirl around, the flashlight beam slicing wildly across the walls, her breath coming in short, sharp bursts that fogged in the cold air. Sweat plastered her dark hair to her forehead despite the chill, and when the light caught her eyes just right, I could see the way her pupils swallowed the warm brown of her irises, leaving only pinpricks of black that seemed too deep, too endless.
"Keep moving," Sarin growled from behind us, his voice low enough that the tunnel walls swallowed most of it, leaving only the vibration of threat.
The concrete beneath our feet began to slope upward, the air growing marginally less oppressive until suddenly the tunnel spat us out into the cavernous belly of a derelict subway station. My lungs expanded gratefully, only to seize again at the sight before us. The station looked like the corpse of civilization, peeling propaganda posters flapped like dead skin from the walls, their bold red lettering screaming commands that no longer mattered: OBEY. REPORT. PURIFY. The smiling faces of city officials stared blankly from the paper, their eyes scratched out by fingernails or bullets.
Emergency exit signs cast a sickly green pallor over everything, making our skin look cadaverous. Nia collapsed onto a bench that had partially melted, its plastic surface warped from some long-ago fire. She pressed the heels of her hands into her eye sockets hard enough to leave bruises, her shoulders shaking not from cold but from whatever war was being waged inside her body.
Sarin moved like lightning, crowding into her space before I could blink.
"How long?" His voice was a blade pressed to the throat. It was quiet, but with lethal intent.
The silence stretched. A drop of condensation fell from the ceiling with a sound like a gunshot. Slowly, Nia lowered her hands. In the ghastly green light, her face was a death mask. Skin stretched too tight over sharp bones, lips cracked and bleeding where she'd worried them with her teeth. But it was her eyes that stopped my heart. The pupils had expanded so much that only a thin ring of brown remained, like a solar eclipse viewed through smoked glass.
"Since last night," she admitted, the words dragged up from somewhere deep and wounded. "The safe house...I thought it was just exhaustion. Then the whispers started."
My stomach dropped through the floor. The granola bar I'd choked down hours earlier turned to cement in my gut. "You're infected."
"Not fully." Her laugh was a broken thing, all sharp edges. "Not yet. But I can feel it...like spiders crawling under my skin, spinning webs in my veins." Her fingers twitched toward the knife at her thigh, a subconscious gesture that made Sarin shift his weight, ready to intervene. "I can hold it off. For now."
Sarin dragged a hand through his filthy hair, leaving dark streaks of grime across his forehead. The barcode on his neck stood out starkly in the low light. "We don't have time for this."
"Then make time," Nia snarled, surging to her feet with a violence that sent the bench screeching backward. For a heartbeat, something not entirely human flickered across her face. A ripple beneath the skin, a wrongness in the way her head tilted. "Because if I turn? I won't just be another Antler. With what I know? I'll lead them straight to every last safehouse, every cache, every fucking rat hole in this city."
The implication hung between us, toxic and unavoidable. Sarin's gaze cut to me, and in that moment I understood with crystalline clarity what he was about to ask. My blood turned to ice.
"Your blood," he said, the words dropping like stones into still water.
I stiffened, my arms crossing protectively over my chest. "What about it?"
Sarin closed the distance between us in two strides. Up close, I could see the fine tremors running through his hands. Not from fear, but from exhaustion, from the constant adrenaline that had been burning through his system for days.
"If you're immune, there's something in your blood that fights the infection. We can use it to buy her time."
Nia let out a wheezing laugh that dissolved into a cough. "You're not a fucking scientist, Sarin. You can't just--what?--drip her blood into my veins and call it a cure?"
"No," he admitted, his eyes never leaving mine. "But I know someone who is."
***
The lab was hidden beneath an abandoned pharmacy, accessible through a false wall that smelled of rotting wood and dead mice. One moment we were surrounded by the detritus of civilization, toppled shelves spilling expired medications, shattered glass crunching underfoot, the next we were stepping into a sterile nightmare.
The contrast was jarring. Harsh fluorescent lights buzzed overhead, illuminating a space that was equal parts hospital and mad scientist's lair. Centrifuges hummed on stainless steel tables, their clear tubes filled with liquids of varying colors and viscosities. Microscopes sat beside weapons, their lenses gleaming like watchful eyes. The air smelled of antiseptic and something coppery, with an undercurrent of ozone that made the hair on my arms stand up.
A figure in a stained white coat stood with their back to us, shoulders hunched over a workstation. My breath caught.
"Rina?" My voice cracked like a teenager's, all the fear and hope of the past months distilled into two syllables.
She turned slowly, as if weighed down by invisible chains. The woman who faced me was both the Rina I remembered and a stranger. Her once-vibrant curls hung lank and streaked with premature gray, framing a face that had aged a decade in months. But her eyes, those sharp, calculating eyes that missed nothing, were the same. The sight sent a jolt through me, equal parts relief and dread.
"Cat." Her voice was flat, devoid of the warmth I remembered. "I wondered when you'd show up."
Sarin stepped forward, cutting through the tension like a knife. "We need a vaccine."
Rina's gaze flicked to Nia, taking in her feverish tremors, the unnatural sheen to her skin. Her nostrils flared slightly as she inhaled whether smelling the sickness or committing it to memory, I couldn't tell.
"You're too late."
"No." I stepped forward before I could think better of it, rolling up my sleeve with jerky movements. The scars on my forearm stood out pale against my dirty skin. "Not if we use me."
Something flickered in Rina's eyes. Guilt? Resignation? Before her professional mask slammed back into place. "You don't know what you're offering."
"I know I'm the only one who survived ZERA without turning." I thrust my arm toward her, my pulse jumping visibly beneath the thin skin of my wrist. "Take what you need."
For a long moment, she just stared at me. Then, with a sigh that seemed to come from the depths of her being, she reached for a syringe.
***
The extraction hurt more than I expected. The needle was cold against my skin, a foreign intrusion that burned as it pierced the vein. My blood looked impossibly dark in the vial, almost black in the fluorescent light. Rina worked with mechanical precision, separating plasma from cells with practiced movements that spoke of too much recent practice.
Beside me, Nia slumped in a chair that had been bolted to the floor. A detail I tried not to think about. Her breathing was erratic, her fingers spasming against the armrests. Every few minutes, her entire body would jerk violently, her eyes rolling back until only the whites showed. Thin trails of blood seeped from her nose, her ears, the corners of her eyes.
"She's syncing," Rina murmured without looking up from her work.
Sarin's hand tightened around his pistol, his knuckles bleaching white. "With what?"
"The network. The Antlers." Rina's voice was detached, clinical, as if discussing the weather rather than the unraveling of a human mind. "ZERA links nervous systems. Creates a hive. Right now, she's hearing them. Seeing what they see."
Nia whimpered, a sound so unlike her usual bravado that it made my chest ache. Her fingers clawed at the chair, leaving red crescents in the vinyl. "They're... everywhere... like ants... under the city..."
I grabbed her hand without thinking. Her skin burned against mine, fever-hot and damp.
"Nia, stay with me. Look at me."
Her head snapped up with unnatural speed. When her eyes opened, they weren't hers anymore. The pupils had expanded to drown the irises, leaving only pools of endless black that seemed to swallow the light. Her mouth opened, and the voice that emerged was layered, discordant, a chorus of whispers speaking in unison.
"She sees you."
I recoiled, my back hitting the edge of a table hard enough to rattle the equipment. Rina didn't flinch.
"Hold her down."
Sarin moved like a striking snake, his body pinning Nia's thrashing form to the chair. The muscles in his arms stood out in sharp relief as he fought to contain her convulsions. Rina approached with the syringe, now filled with a clear liquid that shimmered oddly in the light.
The needle plunged into Nia's jugular.
What happened next wasn't a scream. It was the sound of reality tearing. Nia's back arched impossibly, her spine bowing until I heard vertebrae protest. The sound that ripped from her throat was a cacophony of frequencies, a hundred voices shrieking in dissonant harmony. The lights flickered wildly, glassware shattering as the vibrations hit resonant frequencies.
Then... Silence.
Nia collapsed like a marionette with its strings cut, her head lolling against Sarin's chest. For one heart-stopping moment, I thought we'd killed her. Then, she gasped. A blink. Her eyes were hers again, though swimming with pain and confusion.
She touched her throat with trembling fingers.
"What the fuck was that?"
Rina set the empty syringe aside with hands that shook slightly. "A stopgap. It won't cure her. But it'll buy us time."
Sarin's voice was gravel. "How much?"
Rina met his gaze squarely. "Until sundown."
***
Nia slept fitfully on a cot in the corner, her dreams written across her face in twitches and grimaces. I sat beside her, counting each ragged breath like a miser counting coins. In sleep, she looked younger, the hard edges smoothed away, the constant tension in her jaw relaxed. Just a girl, not the razor-sharp survivor who'd dragged me through hell.
Her fingers spasmed suddenly, clutching at empty air. I caught her hand without thinking, startled by how cold it had become. Her eyelids fluttered, revealing slivers of white.
"They're in my head," she whispered, her voice raw. "I can feel them... moving... building..."
I squeezed her hand, unsure what to say. Across the room, Sarin and Rina argued in hushed tones that nevertheless carried in the sterile space.
"We need to move," Sarin growled, his silhouette tense against the glow of a computer screen.
"She won't survive another run," Rina countered, her arms crossed.
"She won't survive if we stay."
I turned back to Nia just as her fingers clamped around my wrist with bruising force. Her eyes flew open, fully black again for one terrifying second before clearing.
"Cat." Her voice was urgent, lucid. "They're coming."
As if on cue, the lights flickered. A high-pitched whine built in the walls, vibrating through the metal tables, the glassware, the fillings in my teeth. It resolved into something almost like voices, whispering from every surface at once.
Then the walls began to scream.
Sarin was moving before the first horn sounded in the distance. "We're out of time."
Nia swung her legs over the cot, swaying but determined.
"I can run."
Rina shoved a bag of supplies into my hands. "Go. Now."
I hesitated, looking at the woman who'd once been my only friend. "What about you?"
Her smile was thin, bittersweet.
"I've survived worse."
The last thing I saw before we fled into the tunnels was Rina lifting a detonator, her thumb hovering over the button.
Then the world exploded behind us in a fireball that painted the tunnel walls orange for one brilliant, terrifying moment before the darkness swallowed us once more.