I tried to think of something to say, but all I could think about was the 1918 flu, which didn't seem like a scintillating topic of conversation. Sometimes I hate my brain.

Jen finally broke the silence.

"Maybe she's not coming."

I checked the time on my phone. Mandy was ten minutes late, which was not like Mandy. We're talking about someone who carries a clipboard.

Jen was looking down the street toward the nearest subway stop, and I got the unpleasant idea that she was thinking about leaving.

"Yeah, sorry. I'll call her." I scrolled up shugrrl and pressed send. Six rings later I got Mandy's voice mail.

"Must be on the subway," I said, about to leave a message, but Jen reached out one hand, touching me on the wrist.

"Hang up and call her again."

"What?"

"Wait a second." She watched a truck pass, then nodded at the phone. "Hang up and call again."

"Okay." I shrugged—that's Innovators for you—and pressed send.

Jen cocked her head, then took a few steps toward the wall of plywood that surrounded a derelict building next to us. She put her hands on the wood and leaned close to it, like she was doing a psychic reading of the layers of graffiti and posters.

Again six rings.

"Uh, Mandy," I said to the voice mail, "you said this morning, right? We're here; let us know where you are."

Jen turned around, a strange look on her face.

"So, let me guess," she said. "Despite all her cool hunting, Mandy has really Top 40 taste in music."

"Uh, yeah," I said. Maybe Jen was psychic. "Mandy pretty much only listens to…" I named a certain 1970s Swedish mega-group whose name is a four-letter word, definitely both band and brand and therefore banned from this book.

"I thought so," Jen said. "Come here. And redial."

I stood next to her and pressed send yet again.

And through the shaky plywood wall we heard tinny cell-phone tones playing a certain unforgettable ditty.

"Take a chance on me…."

"HELLO?" I POUNDED ON THE WOOD. "MANDY!"

We waited. No response.

I redialed once more to make sure.

"Take a chance on me…" dribbled out from behind the spray paint and advertising covering the plywood barrier.

"Okay," Jen said. "Mandy's phone is in there."

Neither of us asked the obvious question: So where was Mandy? Somewhere else altogether? Inside but unconscious? Something worse than unconscious?

Jen found a spot where two pieces of the plywood were chained together like double doors and pulled them apart as far as the fat padlock allowed. Shielding her eyes, she peered through the narrow gap.

"One more time, maestro."

I pressed send, and the little tune repeated. The refrain was starting to drive me crazy, even more than it usually did.

"There's a phone flashing in there," Jen said. "But that's all I can see."

We backed into the street, getting a better look at the derelict building. The upper-floor windows were bricked up with cinder blocks, dead gray eyes staring down at us. A coil of razor wire topped the plywood barrier around the ground floor, the fluttering remains of plastic bags collected on its spikes. An arm's length of unspooled cassette tape was caught on the wire, the light wind making it undulate and flicker in the sun.

The building must have been abandoned for months. Maybe years. I mean, cassette tape?

"No way in," I said, but found that I wasn't talking to anyone.

Jen was next door, already up the front-stoop stairs and stabbing buzzer buttons at random. The intercom popped, and a garbled voice queried her.

"Delivery," she said loudly and clearly.

The door buzzed. She opened it, stuck her foot in, and waved at me impatiently to follow.

I swallowed. This was what I got for hanging out with an Innovator.

But as I may have mentioned or implied, I'm a Trendsetter. Our purpose in life is to be second in line, to follow. I bounded up the steps and grabbed the outer door just as the buzz came again and she pushed her way inside.

At the top of the third flight of stairs a tousle-haired man was waiting, his head sticking out his door. He looked at us sleepily.

"The delivery guy's right behind us," Jen said, and kept on climbing.

A half flight up from the sixth floor we found the door to the roof. A cagelike contraption sealed us off from the last flight of stairs, the usual precaution to keep people from getting into the building from topside. Of course, the door could be opened from the inside in case of fire, but across the push bar a big red sticker was plastered:

WARNING: ALARM WILL SOUND IF OPENED

I panted, recovering from the climb, relieved that we couldn't go any j farther. Even if Jen was an Innovator, breaking into an abandoned building wasn't my idea of cool. Having thought about it for a minute, I was figuring we should call the police. Mandy must have been mugged, her phone tossed into the derelict building.

But where was she?

"You know the trick to these alarms?" Jen asked, placing one finger lightly on the push bar.

My relief faded. "There's a trick?"

"Yeah." She pushed, and an earsplitting screech filled the stairway, loud enough to be heard by everyone in Chinatown.

"They stop on their own eventually!" she shouted above the alarm, and darted through the door.

I covered my ears and looked back down the stairs, imagining annoyed tenants emerging from every door. And then I followed Jen.

The roof was tar, painted silver to keep the summer sun from boiling the people who lived on the top floor. We pounded across it, the alarm still shrieking like a huge and angry teakettle behind us.

The next building over, the one we were trying to break into (correction: that Jen was trying to break into—I was just along for the ride), stood a bit shorter, a drop of six feet or so. She sat on the edge and jumped, landing on black and ragged tar with a thump that sounded painful.

I climbed partway down, clinging to the edge, falling the least possible distance but still managing to twist my ankle.

I scowled as I limped after Jen. It was all the client's fault. A hundred pairs of shoes and they'd never sent me a sneaker optimized for urban burglary.

The roof door of the abandoned building opened with a metal screech, hanging on one hinge like a dislocated shoulder. Behind it was a dark staircase that smelled of dust and old garbage and something as sharp and nasty as the time my parents' apartment had a dead rat in the wall.

Jen looked back at me, showing a bit of hesitation for the first time.

She opened her mouth to speak, but at that moment the alarm from the next building stopped, the silence hitting us like a hammer.

Through the ringing echoes in my ears I thought I heard an annoyed voice on the roof behind us.

"Go on," I whispered.

We went down into the darkness.

Walking around New York, looking up, I often wonder what goes on behind all those windows. Especially the empty ones.

I've been to parties in squats, old buildings taken over by enterprising homesteaders who do their own repairs. And everyone knows that crack-heads and homeless people occupy abandoned buildings, inhabiting an invisible reality behind the blank windows and cinder blocks. There's this rumor that Chinatown has its own secret government, an ancient system of laws and obligations brought over from the old country, which I'd always imagined being run from inside a derelict building like this, complete with town meetings and trials and punishments meted out. Basically anything could be going on behind those blank and faceless windows.