Between the spinning blades the sky showed through, the dark blue of early evening.

In my days searching for Morgan’s apartment, I’d often seen this building from the outside, a magnificent column of brick, windowless and ten stories high, like a prison balanced on the river’s edge. The inside was just as cheerless, the greasy machines layered with a slapdash coat of gray paint and bird droppings. The scant sunlight pulsed in time with the fans’ rotation. The air was drawn steadily toward the fans, carrying dust and the occasional stray feather upward.

I searched the huge space nervously—my peep hearing was useless. But there was nothing unexpected in the jumble of maintenance equipment, garbage, and empty coffee cups. Whatever my quarry was—mutation or longstanding strain of the disease—its pet peeps weren’t preying on the workers who kept these fans going.

But where had the cat gone? That last echoing yowl must have come from in here, but the doors to the boardwalk and piers outside were locked.

The only way out that I could find was a set of metal stairs descending into the earth. I tapped my flashlight on the handrail, sending a clanging beat into the depths. A few seconds later, the peep cat let out a long nyeeeeow.

The creature was leading me down.

“I’m coming,” I muttered, flicking my flashlight back on.

Below was a world of pipes and air shafts, cold water seeping through the concrete that held back the river, staining it with black bruises. The stairs kept going down, angling away from the river until the salt smell of the Hudson faded behind me and the walls were made of the granite bedrock of Manhattan. I was under the PATH tunnel now, in the service area that accessed its tangle of cables and shafts. Chip had a picture in his office of the huge machine that had bored this tunnel: a steam-powered drill crawling through the earth, the source of all his nightmares.

My flashlight fell on a sign hanging from chains draped across the stairs:

DANGER

Area Closed

As if answering my hesitation, the cat yowled again, the cry rising up from below like a ghost’s.

I paused, sniffing the air, the hair on my neck rising. Under the dampness and grease and rat droppings, a strange scent lay, massive and unfamiliar, like a heavy hand on my chest, it wasn’t the scent of peeps or of the deep earth. It was the same foul smell I’d scented the day before. Like death. Deep in my genetic memory, alarms and flashing lights were going off.

I swallowed and stepped over the sign. As my duffel bag brushed the chains, they creaked sullenly with rust.

This far down, the earth looked wounded, wet fissures splitting the granite walls. The darkness inside seemed to repulse my flashlight and sent back long echoes from my footsteps. I saw no more empty coffee cups—every piece of garbage looked smoothed down by time, half rotted away. I remembered Chip saying that PATH workers had abandoned this place, and I could see why.

Or at least, I could feel it: a cold presence on top of the evil smell.

Finally the stairs ended at a rupture in the rock, a fissure large enough to walk into. I stepped inside, my flashlight glinting off mica-strewn granite. The shadows around me turned jagged.

This was the deepest I had ever been.

The air had fallen still, so I smelled the brood before I heard them. They were huddled together in a ravine of stone, a few thousand rats and their peep cat. Myriad eyes glittered back at me, unafraid of the flashlight.

The cat blinked, yawning, its eyes glittering red.

Red? I thought. That was odd. Cats’ eyes should be blue or green or yellow.

“What’s with you anyway?” I asked the peep cat softly.

It just sat there.

The posse of big fat rats still surrounded it, an entourage of heavy, pale bodies, larger than any rodents I’d ever seen on the surface. All the rats were the color of dried chewing gum, their eyes pink, bred almost to albino from generations in darkness.

I carefully pulled a video camera from my duffel bag and swept it across the brood. Dr. Rat would be thrilled to have footage of these deep-dwellers in their natural habitat.

In the silence, a barely audible sound began to make itself heard.

At first, I thought it was the PATH train rumbling past again. But the noise didn’t build steadily. It came and went, much slower than the sound of the fans. I felt the tiny hairs on my arms moving one way and then the other and realized that the air in the cavern was being pushed in and out, as if a slow and huge bellows was operating.

Something down here was breathing. Something huge.

“No,” I whispered.

In answer, a spine-melting sound washed through the cavern on a fetid breeze, like the moan of some titanic beast. It was so low-pitched that I felt more than heard it, like the buzz of power lines that my peep senses sometimes detect. Every nerve in my body screamed at me to stand up and run away, the sort of panic I hadn’t felt since I’d become a hunter.

The sound passed away, though the air still shifted back and forth.

The peep cat winked its eyes at me in satisfaction.

Okay. I was leaving now … and taking the cat with me. I put the duffel bag aside. If this worked, I was going to have to run fast, carrying as little as possible.

I pulled out my second can of Crunchy Tuna and slipped my gloves on. There was no point in using my knockout injector, which would overdose the cat.

The brood stirred when they smelled the cat food. I waited, frozen, letting the scent carry to the peep cat.

The almost-human intelligence on its face faded, replaced by the same dull look that Cornelius gets when it’s feeding time: pure animal desire. At least the creature wasn’t some sort of diabolical genius—it was just a cat, really, and a diseased one at that. “Come on, kitty,” I said.

It took a few steps toward me, then sat down again.

“You know you want it,” I murmured, lapsing into my kitty voice and fanning the smell toward the cat. The scent of the huge, hidden thing stirred, and a trickle of sweat coursed down my side.

The cat stood again and moved gingerly across the horde of rats, like someone stepping through a tent crowded with sleeping people. They barely stirred as it passed.

But then it stopped again, a few feet away.

“Extra nummies?” I nudged the Crunchy Tuna a little closer.

The peep cat just cocked its head. It wasn’t budging.

Then I remembered Dr. Rat’s perfume of Cal, the family scent distilled into pure essence. Perhaps smelling was believing.

I pulled out the tiny vial and opened it, waiting only a few seconds before screwing the bottle top closed again, not wanting to rile up the horde of rats.

As the smell spread throughout the room, the brood stirred like a single entity restless in its sleep. Snufflings echoed like a horde of tiny whispers around me. The rats would wake up fast once I made my move.

The cat stood up again, stretching, then took a few steps closer to the can of Crunchy Tuna. It remained only inches out of arm’s reach, now staring at the can instead of me, nose quivering, suspicion and curiosity at war inside its little brain.

Of course, it was a cat, so curiosity won…

I snatched the creature up from the floor and squashed it to my chest. Leaping up and spinning around, I dashed back through the rough stone fissure, my flashlight bouncing maniacally off the walls.

The cat let out a disgruntled meow, and squeaks sounded from behind, a sudden panic spreading as the brood realized its master was gone. I reached the stairs and bounded upward, the metal banging like a gong under my boots. The cat fought, yowling and raking my chest, its claws catching the fabric of Garth Brooks’s face in a death grip. But it couldn’t escape my gloved hand.