I barely glimpsed her before she struck, barreling out of the darkness and crashing into me, as hard and solid as a suitcase full of books. The impact knocked my breath away and threw me to the ground. Long fingernails raked my chest, shredding my hazmat suit. I blindly swung a fist and connected with hard muscle, driving a grunt from the peep.

“Patricia!” I shouted, half guessing, and she hissed at the sound, scrambling away from the anathema of her own name. I was right—it was Joseph’s wife. The light came from behind her now, igniting a shimmering halo of feathers wound into her hair and sticking to her skin. With her long fingernails and half-starved face, she looked like a human partly transformed into an awful bird of prey.

She readied herself to spring at me.

“ ‘I’ve got friends in low places,’ ” I sang—the only Garth Brooks song that came to mind. The refrain halted her long enough for me to tear the shredded hazmat suit the rest of the way open.

Patricia Moore stared at my chest in horror; the jolly country singer stared back.

“Oh, yeah!” I said. “She’s my cowboy Cadillac!”

Her eyes widened and she screamed, spinning away to scuttle up the tunnel toward the light.

Another anathema awaited her there: her husband, faceup on the floor. I turned and scrambled deeper into the darkness, sweeping the dirt floor wildly with my palms. Where was my damn flashlight?

My racing brain wondered how long she’d been tracking me. Had she followed me from downwind since I’d dropped into the tunnel? Or maybe she always lurked near her husband, just as Sarah had stayed close to Manhattan.

Suddenly my knuckles grazed hard metal, sending the flashlight’s cylinder rolling farther into the darkness. I reached out, grasping blindly, and at that moment my ears split with Patricia Moore’s scream—fear for her husband and horror at the sight of his beloved face, mixed up in one terrible cry that echoed through the tunnel.

My hand closed on the flashlight.

She was already headed back, loping toward me on hands and knees, growling like a wolf.

I covered my eyes with one hand, turned the flashlight on her, and switched it to full power. Her feral grunts choked off, and the tunnel flooded with light so strong that the blood-pink veins in my eyelids were burned into my vision.

A moment later, I flicked it off and opened my eyes. Against the sunlight streaming down the shaft, I could see Patricia Moore crouching in the center of the tunnel, head pressed against the feather-strewn dirt, motionless, as if paralyzed by one too many insults to her optic nerve.

I set the flashlight on low and found my duffel bag, only a few yards down the tunnel. Pulling out the spare injector and loading it, finally thankful for all those tedious drills in Hunting 101, I whirled to face her. She still hadn’t moved.

Perhaps Patricia had despaired, thinking that her husband was dead, or maybe it was too much to keep fighting in a world that included my rendition of “Cowboy Cadillac.” But for whatever reason, she didn’t move a muscle as I approached across the feathered floor.

I reached out and jabbed her in the shoulder. She winced as the needle hissed, lifted her head, and sniffed the air.

“You’re one of Morgan’s?” she asked.

I blinked. My vision was still spotted with tracers, but her expression seemed thoughtful, almost curious. Her voice, like Sarah’s, was dry and harsh, but the way she said the words sounded so reasonable, so human.

“Yeah,” I answered.

“You’re sane?”

“Um … I guess.”

She nodded slowly. “Oh. I thought you’d gone bad, like Joseph.” Her eyes closed as the drug took effect. “She says it’s coming soon…”

“What is?” I asked.

She opened her mouth again but fell into a heap without making another sound.

Maybe I should have headed back to the surface to rest up, reload, and share my revelations about the parasite’s new tricks. Maybe I should have waited right there for the transport squad, brought them in by GPS and cell phone.

Both of my captives had been so unpeeplike—Joseph facing the orange late-afternoon sun as if the light didn’t faze him, Patricia speaking so clearly once she’d identified my scent.

Are you sane? she’d asked. Yeah, right. I wasn’t the one living in a tunnel.

But it reminded me of the way Sarah had changed after I’d cornered her, asking about Elvis, peering into my eyes without terror. Maybe I should have mentioned this to someone right away.

Maybe I should have wondered more about what was coming soon.

But I didn’t wait around. I still had a peep cat to catch.

After handcuffing Patricia Moore, I called the transport squad, giving them precise GPS coordinates for the captives. They wouldn’t even have to disturb Manny and his tenants to collect the peeps. They could simply put on Con Edison uniforms, set up a fake construction site on the Hudson River walk, and cut their way in through the metal 22 grate at the end of the ventilation tunnel.

They didn’t need me, and with a high-priority work order from the Mayor himself in hand, it made perfect sense to follow the tunnel in the other direction: down the slope, the steady breeze at my back, toward the rumble of the huge exhaust fans.

Under the swimming pool again, I listened to the echoes bouncing down the shattered drain. The basement overhead sounded the same—still just a few dozen rats squabbling and skittering among the feathers. The brood hadn’t returned, and nothing had touched the cat food I’d left behind.

I wondered how far down the tunnel the scent would travel, if floating molecules of Crunchy Tuna would tempt the peep cat out into the open. With the wind at my back, I was hardly going to catch it by surprise. I kept my flashlight on medium, not wanting to get jumped in the darkness again.

The slope grew steeper, descending as the tunnel continued. The air became chill around me, and drops of water began to plink from the ceiling. The low rumble of exhaust fans grew in the distance, throbbing like a massive heartbeat at the core of the city.

Then another sound floated up the tunnel, an impatient yowl that cut through the low-pitched thrumming. The cat could smell me now and knew that I was coming. I wondered if it also knew two of its pet peeps had been dispatched.

Just how smart was this thing?

The echoes of the cat’s cry suggested a large open space in front of me. The push of the breeze at my back had strengthened, and the pulsing beat of the exhaust fans grew more distinct.

Then I felt something, a trembling in the earth. Unlike the rumbling of the fan, it was building steadily under my feet, until it made the stones in the tunnel walls vibrate visibly. I knelt on the quivering dirt, suddenly feeling trapped in the narrow tunnel. I peered deep into the darkness, one way and then the other, searching for whatever was coming as I tried to fight off panic.

Then the rumble peaked and began to fall away, fading into the distance, just like … the sound of a passing train.

Chip had been right. The PATH tunnel was nearby, and the rush-hour commute was just beginning. The disturbance hadn’t been some rampaging creature from the depths, just a trainload of New Jerseyites headed home. I stood, feeling like an idiot.

But the earth-shaking passage had left something visible up ahead—strands of stirred-up dust hung illuminated in the air. Flicking the flashlight off, I saw shafts of light filtering into the tunnel. They pulsed brighter and then darker in time with the constant throbbing—I had to be close to the exhaust fans now.

The tunnel ended a little farther on, and I stepped down from its open maw into a vast cathedral of machines. Whirring turbines filled the air with the smell of grease and an electric hum. Above me I could see a huge pair of fans turning at a stately pace, the blades eighty feet across; this was Chip’s ventilation system.