“Sit tight? Yeah, right! I bet Morgan was sitting tight when she got bitten. There’s probably some little rat tunnel that leads all the way up here from the basement!” Her eyes swept the apartment, searching for tiny cracks in the walls, holes that could let the pestilence inside. Already the old fears were stirring inside her.

“Well, maybe a year ago there was,” I said soothingly. “But now there’s steel wool stuffed under that chained-up door, and a ton of peanut butter behind the false wall. The disease is probably contained for the moment.”

“Probably? So you’re asking me to trust my life to steel wool and peanut butter?”

“Poisoned peanut butter.”

“Cal, I don’t care if it’s nuclear peanut butter.” She stood up and stomped into her bedroom. I heard the scrape of vinyl across the floor, the sound of zippers, and the clatter of clothes hangers.

I went to her doorway and saw that she was packing a bag.

“You’re splitting?”

“No shit, Sherlock.”

“Oh,” I said. The sight of her packing had sent a twinge through me. I’d just shared my biggest secret in the world with Lace, and she was leaving. “Well, that’s probably a good idea. It won’t take long to clear things up downstairs, now that we know what’s going on.” I cleared my throat. “You should tell me where you’re going, though, so I can keep in touch. Tell you when it’s safe.”

“No problem there. I’m coming to your place.”

“Um … you’re doing what?”

She stopped with a half-folded shirt in her hands and stared at me. “Like I told you last night: I’m not going back to my sister’s couch. Her boyfriend’s there all the time now, and he’s a total dick. And my parents moved out to Connecticut last year.”

“But you can’t stay with me!”

“Why not?”

“Why would you want to? You don’t even know me! What if I … turn out to be a psychopath or something?”

She returned to folding the shirt. “You? Every time I think you’re talking crazy, I remember what I saw down in the basement, or what’s in there.” She nodded toward the living room, where the thing on the wall lurked. “And nuts or not, you’ve got the inside line on a huge story. Did you really expect me to go off and read textbooks tonight or something? Why do you think I went into journalism anyway?”

My voice went up an octave. “A story? What about keeping this a secret? You promised. Aren’t you supposed to have journalistic ethics or something?”

“Sure.” She smiled. “But if you break your promise and lie to me, I can break mine. So maybe I’ll get lucky.”

I opened my mouth and a strangled noise came out. How was I supposed to explain that I was a psycho, that a raging parasite inside me desperately wanted to spread itself by any means possible? That just standing here in the same room with her was already torture?

“Besides,” she continued, “you don’t want me staying anywhere else if you want to keep this a secret.”

“I don’t?”

She finished folding the shirt. “No, you don’t. I talk in my sleep like crazy.”

By the time we left her apartment, it was the dead of night.

I stabbed the button for the health club repeatedly as we rode down. It didn’t light up.

“Dude, don’t do that.”

“Just making sure Manny locked the elevator.”

Lace shifted her suitcase from one hand to another. “Yeah, but it’ll be open again tomorrow, won’t it?”

“Not for long.” I could requisition a fake court order in the morning, enough to shut down the lower levels for a week or so. And as soon as possible, I was going down there with Dr. Rat and a full extermination team, carrying enough poison to exterminate this particular slice of the Underworld halfway to the earth’s core.

The doormen had changed shifts, and the new guy looked up at us through thick glasses as we crossed the lobby, reflections of the little TVs on his console flickering in them. It gave me an idea.

“Talk to him for a second,” I whispered.

“About what?”

“Anything.”

“Like what’s in your bag?”

I will be avenged! came PNS’s muffled squeak. He was trapped between the spaghetti strainer and a dinner plate, duct-taped together and wrapped in a towel for silence, the whole thing shoved inside the Barneys shopping bag in my hand. I figured his little rat lungs had another minute of oxygen left before I’d have to take the towel off.

“No. Just distract the guy. Quick.”

I steered Lace over to the doorman’s desk, elbowing her until she launched into a rant about her water taking too long to heat up. As the doorman tried to placate her, I eased around to where I could see his security monitors.

The little screens showed the insides of elevators, hallways, the sidewalk outside the building’s entrance, but nothing from the floor below. That was why no one had noticed our comings and goings—the cameras downstairs didn’t work anymore.

Or did they? I remembered their red lights glowing in the dark. This building was owned by an old family, after all. They hadn’t simply walled up the rat invasion; they’d left a secret passage through the locker and turned the cameras to face it. Someone was interested in what was going on downstairs. There could be videotape of us somewhere, waiting to be watched…

“Come on,” I said, pulling Lace away in mid-sentence.

The air outside was cold and damp. I paused to unwrap a corner of PNS’s cage to let him breathe. He squeaked vengeance and rebellion, and Lace glanced at the bag and took a step back.

“You owe me a plate and a strainer, dude,” she said.

“You owe me an earth-shattering secret history.”

“I’d rather have a spaghetti strainer.”

“Fine, take mine when you leave.” I pointed east, up Leroy Street. “We can catch the B on Fourth.”

“What? Take the subway? Go underground all the way to Brooklyn?” Lace shuddered. “No way. We’re cabbing it.”

“But that’s like twenty bucks!”

“Split two ways, it’s only ten. Duh. Come on, we can grab one on Christopher.”

She started off, and I walked a little behind her, realizing that my lifestyle was already changing, and my guest hadn’t even set foot in my apartment yet. I’d considered giving Lace my keys and taking PNS downtown for immediate testing, but the thought of her tromping through my personal space alone had killed that idea—there were books lying around that detailed the few Night Watch secrets I hadn’t already spilled. I’d promised to tell her the truth about the disease, not teach a college course on it.

As we walked up Leroy, I glanced at the loading docks of the big industrial buildings, wondering if any of the brood had found a way up to street level. A couple of rats sat atop a glistening pile of plastic garbage bags, but they had the furry look of surface-dwellers, not the pale greasiness of the brood in the basement.

Then I saw another shape, something lean and sleek moving in the shadows. It had the stride of a predator—a cat.

I couldn’t spot any markings, only a dark silhouette and the shine of fur. The cat in the basement had also been solid black, but so were about a million other cats in the world.

Suddenly the animal froze, looking straight at me. Its eyes caught a streetlight, the reflective cells behind them igniting with a flash. My stride slowed to a halt.

“What is it?” Lace asked from a few yards ahead. At the sound of her voice, the cat blinked once, then disappeared into the darkness.

“Cal? What’s wrong?”

“Um, I just remembered something I didn’t tell you, another vector for the disease.”

“Just what I was hoping for. Another thing to worry about.”

“Well, it’s not very likely, but you should be careful of any cats you see in this neighborhood.”

“Cats?” Her gaze followed mine into the shadows. “They can get it too?!’

“Maybe. Not sure yet.”