"Todd," the man with the gun says, interrupting our hug fest. Dad looks up, happy tears sparkling in his eyes, grinning like a loon. "Our kids aren't here. We have to push on."

Dad's grin fades. He pats my head, then stands. The two men shake hands. There are a couple of women behind the guy with the gun, one white, one Chinese. Dad smiles sadly at the white woman but only scowls at the other one.

"You're sure you want to continue?" Dad asks Gun Guy.

"I have to." He turns to the rest of us. "Any of you know Jimmy Wilkins?" Most of us nod. "Have you seen him?" We shake our heads.

"What about Lindsay Hogan?" the white woman asks.

Linzer.

"The zombies got her," I mutter.

The woman's face hardens. "No!" she snaps. "You're wrong."

"We saw them grab her."

"Where?" she screams.

I turn and point. The woman starts running. "It was on the top floor," I shout. "You're too late. She's dead."

But the woman isn't listening. She's gone.

The Chinese woman asks us if we've seen her son and daughter, but we don't know either of them. She heads off with Gun Guy, the pair advancing swiftly, checking each room as they pass.

"It's madness," I whisper to Dad. "They're gonna get killed."

"I know, love," he says. "But that's what parents do for their kids. I knew I'd probably get eaten when I came looking for you, but did that stop me? Hell no."

I beam at him, so proud. He looks around, smiles at my friends, sniffs at the Muslims, the Indian and Tyler. "Come on," he says. "I'm getting you out of here."

We follow Dad back the way he came. He's moving quickly but he isn't racing. "Slow down," he says as Trev tries to force the pace.

"But the zombies..." Trev gasps.

"You think I don't know about them?" Dad snorts.

"We have to get out," Trev insists.

"That's what we're doing," Dad says calmly. "But if we go flapping around like headless chickens, we'll run into trouble, the way you lot did before I found you. These zombies aren't so tough if you're prepared for them. I've finished off a few of them already." He shakes a metal bar at us - it's red with blood. "But you have to go about it the right way, keep your head, make sure you have the time and space to spot them coming."

He takes a left turn and we pass the staff room. The door's open. I spot a couple of teachers inside, chewing on the remains of some of their colleagues.

"They won't be failing you again," Dad says and we both laugh.

"Straight F's in most courses," I chuckle. "But A-plus in zombie survival!"

"Been a long time since I was a student here," Dad mutters nostalgically. "But I remember the place like it was yesterday. Didn't have any trouble finding my way around."

"How'd you get over here so quickly?" I ask. It feels like we've been running for hours since the gym, but it can't have been more than fifteen or twenty minutes.

"I was working nearby," Dad says. "When I heard about the attacks on the radio, I ran like the wind. I tried calling ahead to check if things were all right but the phones aren't working."

"Then it's true?" Elephant asks. "This is happening in other places too?"

"Yeah," Dad says. "Schools, hospitals, shops, factories, all sorts and all over the place. Getting out of here won't be the end of it. London's in an uproar. But the zombies tend to keep to the shadows. If we stick to the main streets and roads, we should be all right. At least until night."

"What about Mum?" I ask, able to think about her now that I have someone else to watch out for me.

"We'll swing by home, see if she's there," Dad says.

"Can't we call and get her to - "

"Weren't you listening?" he snaps. "The phones are dead. Cells, landlines, the lot. TV stations are down too. A lot of radio stations as well, but a guy I work with has a top-of-the-range radio that picks up all sorts of frequencies. That's how I know it's widespread. It started about..." He checks his watch. "Not quite an hour ago. But I didn't hear about it immediately. As soon as I did, I came." He flashes me a shaky smile. "You didn't think I'd leave you to be gobbled by zombies, did you?"

I want to burst into tears and hug him again, but there's no time. We have to keep moving. We'll be relatively safe in the sunlight once we get out of here. We can hug all we want then.

We move steadily through the school, drawing closer to the front of the building. For the first time since the gym I really allow myself to hope. I don't want to tempt fate but I think we've made it.

We come to a corridor that's only a few turns from the main exit. Everyone's excited. We can virtually smell freedom. There's a fire door ahead of us. Once we push through that, the corridor branches. The right turn leads back into the school. The left will lead us all the way home.

Dad shoves the door. It rattles but doesn't open. He frowns and pushes it again. No joy. "That's not right," he says. "I came through here on my way in."

The Indian kid slides up to the crack in the door and peers through. "It's been locked," he moans. "There's a chain."

"What?" Dad shouts, shoving him aside and squinting through the crack. "Who the hell did that?"

"The mutants," I sigh. As if in answer, I hear a whistle blow somewhere close behind us. "Dad! They're coming!"

Dad stares at me. He starts to ask how I know we're in trouble, then shakes his head and slams the door with his shoulder. "Keep back," he grunts at those around him. "It'll take more than a chain to hold me here."

We stare at Dad as he rams the door again and again. It's a thick, heavy door, designed to slow the spread of flames in case of a fire. The chain is sturdy too. Dad doesn't look to be achieving much but he keeps going, sweating like a marathon runner, totally focused.

I glance back down the corridor and spot four zombies slipping into it. They lock sights on us and slither forward.

"Dad!" I wail.

"I nearly have it," he pants.

Trev throws himself at the door, trying to help. Meths and Seez take turns too. Dad glares at them, but then there's a snapping sound and the door starts to give. "That's the way, boys!" Dad whoops. "Give it everything you have."

They hurl themselves at the door, one after the other. Their arms and shoulders will be black and blue later but they don't care. No matter how much of a battering they take, they don't back down.

Elephant, Stagger Lee, the Indian and the other Muslim kid watch helplessly as Dad and the three boys fly at the door like rabid dogs. I'm a bit farther back, Tyler by my side. I'm looking for anything I can use to fend off the zombies but I'm not having much luck. They're closing in. They could have rushed us by now, but they see that we're trapped, so they're taking their time.

"Dad!" I yell.

"Just another few blows," he wheezes, launching himself at the door again.

More zombies appear at the far end of the corridor, loads of them, a couple of whistle-blowing mutants in the middle, guiding them towards us.

"Dad!"

Dad looks back and whitens. "Holy hell," he croaks.

Meths bangs into the door and it cracks. The hinges give. Meths cheers and starts shaking the door. Dad and Seez join him. There isn't room for Trev - he's been pushed out of the way.

"They're almost on us," I shout.

Dad looks at me, then at the zombies, and curses. "You've got to stall them. We only need a few more seconds."

"How?" I scream. "There's nothing I can do to - "

"Throw them the black kid!" Dad roars.

I stare at him. Tyler stares too, both of us stunned, momentarily forgetting about the zombies.

"Do it!" Dad shouts.

"But he's Tyler," I whisper. "He's one of us. He helped us get - "

"Throw them the bloody chimney sweep or I'll whip you raw!" Dad screams.

And suddenly I'm reacting, doing what he tells me, the way I always do when he loses his temper, because it's easier to obey him than stand up to him. Years of conditioning kick in. Fear takes over. I go into my dutiful-daughter act. The racist in me swims to the fore and rejoices at being set free.

On autopilot, I grab Tyler's arm and hurl him at the zombies.

"No!" he shrieks as he stumbles towards them. "B! No! Help me!"

Tyler crashes into the zombies. All five go down, and the zombies sprawl like bowling pins. Tyler starts to get up. Immediately guilt-stricken and appalled, I reach out to him, desperately wanting to put right what I've done. But before I can drag him to safety, a zombie catches hold and bites Tyler's neck. Tyler chokes and stiffens, blood spurting, and I watch with horror as the other three zombies crowd around and tuck into the tasty human morsel that I've thrown them.