"Hurry up! Just take them off. We need to trade." Fabric rustles. A warm ma.s.s is dropped into my lap. Her clothes.

I pull my shirt over my head, and after taking the concealer out of the pocket, slip off my shorts, holding them in what I a.s.sume is her direction. She s.n.a.t.c.hes them away.

"But first," she whispers, "you need to wrap this around your a you know whats." She drops something else in my lap, a long, thin strap of fabric.

"Wrap this around my what?" I ask, baffled.

"How dense are you? Do I seriously have to spell it out?" When I don't answer, she blurts, "Around your knockers, Fo. No one's going to believe you're a boy if they get a look at those. Even if they are small. Sheesh." She mutters under her breath as I struggle to bind my b.r.e.a.s.t.s, tying the fabric into a knot below my left armpit.

When I'm done, I fiddle with her clothes until I find the shirt. As I pull the stiff, greasy-feeling fabric over my head, I gag. The stench is unreala"sweat, urine, dirt, sewage. I pull on the pants, barely manage to squeeze them over my hips, and, sucking in my stomach, force them to b.u.t.ton.

"You are so fat," Arrin whispers, her voice filled with wonder. "It's a good thing these shorts have a drawstring."

I press on my bony hips. "I'm not fat."

"Don't you know a compliment when you hear one? You're lucky. Even with the drawstring, your shorts will barely stay up on my bony b.u.t.t." Arrin inhales deeply. "And you smell like flowers, I think. I can't quite remember."

Flowers. I remember how they smell. Beds of lavender and forget-me-nots lined my driveway. Lis put lavender in matchless socks and stuck them in her drawers. She always smelled like lavender.

"It's almost time to go," Arrin whispers.

"Where?"

"Up. You're going to pay me back. Double. Tonight. Remember?"

My heart starts drumming. Something in her voice makes me wonder what I have gotten myself into. "How am I paying you back, Arrin?"

She chuckles, and goose b.u.mps shiver down my arms. "You'll see." The air shifts, and then she pulls me to my feet. "Now, someone is stalking my tunnel. You've got to walk behind me and hold on to my shirt. And don't let go! Even if we have to run. Especially if we have to run."

I nod and blindly run my hands over her bony body until I find the back of her shirt. And then we start walking through the black tunnels, and all I can think of is the person who was watching us, who might be about to pounce. Her shirt grows damp from my hand, and my feet squelch no matter how I tiptoe.

Chapter 5.

"Why's the ground so squishy?" I whisper.

"You're walking on dried-up human sewage. Only it's not completely dry," she says, her voice barely audible.

I shudder.

"Haven't you ever been down here, Fo?"

"No," I say without thinking. And surely I'd remember a place like this. Wouldn't I?

"Lucky you. It used to be worsea"a ca.n.a.l of slime that reached up to my knees. I had to hide in it once, buried up to my nose." She says it like she's bragging.

I cringe and wonder if the clothes I'm wearing are the clothes she wore in the sewage.

"Don't you wanna know why?" she asks.

"Why?"

"The militia was hunting me. Almost caught me, too. One of them waded right past me and didn't see me because he didn't look down." She laughs under her breath.

"What happened?" I ask.

"They all got sicka"the militia. They're a bunch of wimps, can't stand the smell down here, I guess. They started barfing up perfectly good food. A total waste. And then they left."

"What is the militia?" I ask. Arrin stops walking.

"Seriously?" she says.

"Yeah."

"You don't know what the militia is?"

I search my muddled brain, trying to put a picture with the word, but come up blank. "I don't think so."

"You know, the guys with the big guns? Who patrol the wall and catch Fecs for the lab? And shoot the raiders on sight?"

"Oh. Right. The guys with guns that guard the wall and catch a whatever a" I have no idea what any of that means, and my brain won't supply the answers.

The shirt tugs against my grasp, and we continue winding through the dark, my feet the only sound.

"Fo, where did you come from?" Arrin whispers after we've walked a while. "It's like you're straight out of a fairy tale, or another dimension."

Sleeping Beauty, I think, just woken from a hundred-year sleep. "I don't know wherea"" Arrin's shirt tears out of my clammy fingers.

A wet smack echoes through the tunnel and then I am knocked onto my back, the impact absorbed by the spongy, damp ground. The breath gushes out of me but stops prematurely as a pair of ma.s.sive hands clamp around my neck. I try to gasp but can't. The hands squeeze harder, crushing my windpipe, and jagged fingernails dig into my flesh.

I claw at the huge hands, wiggle beneath them, try to force air into my body. But I can't. I ball my right hand into a fist and swing at the darkness above my face. My fist contacts rough, hairy skin, and the hands on my neck loosen a fraction. My blood starts to boil as fury fills me, seeping fire all the way to my toes. I pull my hand back again and ball my fingers so tightly my fist trembles. This time when I swing, my entire body bolts energy into the movement. My knuckles contact flesh and bone, the fingers on my neck loosen and fall away, and something crumples on the ground beside me. I roll to my side and gasp for air, pressing my cheek against the slimy ground.

Noise fills the tunnela"grunting, struggling, and breathing loud enough to wake the dead. Arrin whimpers and lets out a cry. I climb to my feet, turn toward her voice, and nearly trip over something. A body. My hands flutter over it; feel the gentle inhale and exhale of a living person; feel broad, square shoulders with lines gouged into the bare skin and a face covered in coa.r.s.e hair. My attacker.

I yank my hands away and stand, shuddering.

The sounds of struggle still haunt the black tunnel. I follow the gasping and grunting and growling and stumble into flailing bodies.

"Arrin?" I ask.

"Help me!" she gasps. I freeze. Help? I can't see anything. If I start kicking, I might kick Arrin. If I punch, I might hit the wrong person.

"Jump on him, Fo!" Arrin calls.

I take a deep breath and halfheartedly throw myself toward the sound of the human skirmish. I land atop a roiling, lurching pile of arms and legs. And then I can tell which is Arrin and which is the other. He's big and muscular with arms like fur-covered clubs. She's a pile of skin and bones. I grab a handful of greasy, coa.r.s.e hair and yank his head backward. Arrin grunts. Without warning, the man jerks twice and goes limp.

"Get him off me!" Arrin cries. I push the man over, and my hands come away wet. "Hurry. They travel in packs." Arrin grabs my hand, and we start staggering through the dark. Before my heart has had time to calm, we stop.

"b.l.o.o.d.y h.e.l.l," Arrin whispers, her hand tightening in frustration on mine.

"What's wrong?" I ask.

"We're lost." She yanks me forward once more.

After a few minutes of staggering, I make out a hazy glow down a tunnel to my right and tug Arrin to a stop. "Light," I say.

Arrin curses and pulls me into a crouch. "Don't say a word," she warns. "Or make a sound! Walk on the outside edge of your feet, Fo. Because if they hear you, they'll murder you. And I'm not going to save your sorry, fat b.u.t.t a third time."

"Even though I just saved you?" I ask, trying to understand her logic.

"Whatever! I had that under control. Now shut up," she hisses.

I struggle to balance on the outside of my feet and manage something close to silence. But as we approach the light, confusion fills me. They don't look like murderers. Arrin stops.

A hollow-cheeked woman sits on the ground beside a candle. Four children huddle at her feet. One child, the tallest, a boy who can't be more than ten, holds a dingy plastic container in his hands. He fishes around in the container and pulls out something long and thin. It curls and coils in his fingers. I blink and stare at the child holding the earthworm, wondering what he's going to do with it.

He hands it to a wisp of a childa"a girl, I thinka"wearing an oversize T-shirt that hangs down to her k.n.o.bby knees. The girl shoves it into her mouth, chewing and sighing like she's eating chocolate.

My jaw drops, but I snap it shut. I can taste the sewer when I breathe through my mouth.

The boy gives each child a worm, then hands one to the woman. Once everyone else has had one, he takes one for himself, eating the wriggling creature in little bites, savoring it.

"Why are they eating worms?" I whisper.

"Obviously their father, wanting to live a life of leisure inside the wall, abandoned them," Arrin whispers, voice bitter.

"No way. A father wouldn't do that."

"Wanna bet?" She squeezes my hand, mashing the bones together. I gasp and try to yank my hand away, but she clings to it. "Shut up, Fo!"

In one collective movement, all four children whip around to face us. A knife appears in the boy's hand. Another appears in the wispy little girl's hand. They stare into the darkness, poised on the b.a.l.l.s of their feet. The woman, eyes panicked, leans forward and blows out the candle, and the safety of darkness swallows them.

Arrin yanks me in the opposite direction of the worm eaters. We run until she jolts to a dead stop, and I slam into her back. She groans and drops my hand, but our palms don't come loose. I pull and our flesh peels apart.

"Why were our handsa""

"Shhh!" Arrin hisses, smacking me. "You are going to get me killed! Just shut up long enough to pay me back!"

There is a wet thud by my feet. "I crashed into a wall and hit my head." Arrin's voice comes from below. "And the guy in the tunnel cut me. I've got to rest. Sit, if you want."

I don't sit. Not when I know what coats the floor.

"Here's what you're going to do, Fo," Arrin says a few minutes later. "My nine-year-old brother was picked up yesterday morning. You're going to create a distraction so I can get him out. After that, you're on your own."

"Why was your brother picked up?" I ask.

"He's a Level Three," says Arrin, as if it's the most obvious reason in the world.

"A Level Three what?"

"Where are you from, Fo? How can you not know what a Level Three is?"

"I'm from a" Fuzz fills my brain. I can see my house, see my brother, remember how my sister smells, remember my dad teaching me how to shoot and my mom cooking pancakes on Sunday morning. I can even remember how to make music with my fingers. But I can't remember where I have been.

"That was a rhetorical question, moron. I get it. You don't remember. Help me up." I pull Arrin to her feet. "Next rain gutter we see, we're going topside."

Chapter 6.

The late-afternoon sky burns my vision. I press my palms against my watering eyes and fill my lungs with clean, bright air.

"The bad news is, we're still about half a mile from the wall," Arrin says, sliding the grate back over a rain gutter. "Good news is, I don't think there's a hive between us and there. All we'll have to watch out for is patrolling militia and raiders. But raiders usually don't come around the militia's camp, and they never come out before sunset."

I pull my hands from my face and squint. We stand on the side of a deserted street surrounded by crumbling factories, abandoned cars, and broken traffic lights. Garbage and tumbleweeds blow down the street, the only noise in this arid world of silence.

Arrin starts to run. I lope to her side and for the first time, truly see her.

She is tiny, the top of her greasy head barely as high as my chin. One of her eyes is bruised and nearly swollen shut, and her lip is split. Greasy-looking grime covers every inch of her skin and darkens her pores into a constellation of black dots. Yet, beneath the dirt and filth, she is a child. She glares at me with cold blue eyes.

"Why are you staring at me, Fo?"

"How old are you?" I ask.

She thrusts her square chin and pointy nose forward. "Thirteen."

"So am I," I say. I can remember my birthday cake, remember the pink candles. Thirteen of them.

Arrin raises one dark eyebrow and looks me up and down. "Liar. You're an adult."

"No. I remember turning thirteen," I say. My hand wanders up to my throat again, feeling my collarbone for a fine chain. But there is nothing hanging around my neck.

Arrin shakes her head. "What you are is messed up in the head. You have hips. And knockers. And you look like an adult." Arrin tilts her head to the side, her eyes suddenly alert. She grabs my arm and yanks me toward the nearest building. We dart through a missing door and Arrin dives into the shadows. I crouch beside her, perplexed.

"What's wrong?" I mouth.