Three days pass. I'm locked inside my cell. Nobody visits, not even Reilly.

No food.

My stomach doesn't rumble. I don't feel hungry. But I'm twitchy. I find myself obsessing about the gray gunk that I used to be fed, craving more. I get shooting pains through my head and insides. Sometimes I have to double over and grit my teeth until the pain passes. My vision is getting worse, even though I keep adding the drops. Conversely, for some strange reason my sense of smell and hearing are improving. The noises of the complex often grind away at my brain until I have to clamp my hands over my ears to block them out.

Last night, when I was lying on my bed, I blacked out for a while, the way I used to when I fell asleep. The next thing I knew I was on my feet, head butting the mirror. I'd smashed it to pieces but was still butting it, snarling softly.

I've tried to stay active since then, exercising, walking around my cell, doing push-ups and squats. I won't give in to fear. I won't. Let them starve me. I don't care. I'm not going to play their game. I'd rather die than become a killer.

Really? a small part of me whispers.

"Yeah," I tell it.

But my voice quivers and I'm not entirely sure that I can believe myself, that I can stay strong and true.

Working out. Keeping busy. Wanting to cling to consciousness for as long as I can, hoping that if I stay focused, it will help.

I've been thinking a lot about Mum and Dad. I'd managed to put thoughts of them on hold over the last few weeks, but Josh's threat about my mum has set me wondering again. I'm pretty sure they're not prisoners here - if Josh really had a card like that up his sleeve, he wouldn't have revealed it so casually - but are they squeezing out an existence in a similar complex? Were they killed? Turned into zombies? Or have they carried on as normal in a world not much different from the way it was on the day of the attacks?

By what I was told, millions of people were killed in London, and hundreds of thousands were turned into zombies. But maybe Josh and the doctor were lying, feeding me misinformation to make me think the situation is worse than it really is.

As I'm driving myself mad thinking about the possibilities, the door suddenly slides open and Josh and Reilly stomp into my room. They both look impassive. I was doing squats but I stop and stand. Stare at the pair of them defiantly.

"I thought you might have had a change of heart," Josh says. The sound of his voice makes me wince, it's so loud.

"You forgot," I sneer, and pull up my T-shirt to expose the hole in my chest. "I don't have a heart."

Josh sighs. "I'm not enjoying this, Becky. I can rustle up some gruel for you in a matter of minutes if you give me the word."

"I can give you two words," I tell him. "The second is off. Can you guess the first?"

Josh shakes his head and laughs - to my sensitive ears, it's like a jackhammer. "I really hope you relent and come to see things our way," he says. "You and I could be great friends if you cut yourself a little slack."

"I'd cut my own throat before I'd claim you as a friend," I grunt.

Josh gasps theatrically, then nods at Reilly. "Take her through."

"Where?" I ask, tensing, thinking this is it, they're taking me back to the pens to dump me with the other zombies.

"Zom HQ," Reilly says, and holds up a pair of handcuffs. "I'm going to have to ask you to wear these on the way there and back."

"What if I don't want to?"

"I have orders to force you if necessary," he says.

"I don't mean about the cuffs," I snort. "Zom HQ - I don't want to go."

"Aren't you lonely?" Reilly asks. He's speaking more softly than usual. I think he knows that noises hurt me.

"No," I lie. "Even if I was, I'd rather suffer loneliness than sit with that shower of vipers. I've no friends there. They can all go hang."

"Even Mark? He wasn't involved with any of the experiments."

I shrug. "He wants to be."

"That's because he hasn't seen what they get up to." Reilly jangles the cuffs. "It's not an option, B. They're determined to send you there. I don't want to hurt you, but if you leave me no choice..."

I roll my eyes and glare at the smiling Josh. "All right. I'll come peacefully. Give me the bloody cuffs."

The zom heads look astonished when I walk in. They also look unhappy to see me. It's a good thing I wasn't expecting a warm welcome.

"What's she doing back here?" Tiberius shouts at Reilly as he unlocks my cuffs.

"I know you've been missing her, so I brought her along to cheer you all up," Reilly deadpans, then exits.

Rage squares up to me as I head towards my regular couch.

"What was all that crap about when we were experimenting on the zombies?" he growls.

"You might call it an experiment," I spit. "I call it torture and murder."

"You can't kill zombies," Rage says, looking genuinely surprised.

"Yeah, I know, they're already dead," I sneer. "Why don't you change the track? I've heard that one too many times. It's the regular excuse round here to do whatever the hell you want."

"But they are dead," Cathy protests. "It doesn't matter what happens to them."

"You're dead too," I remind her.

"That's different," she growls. "We're different."

"Yeah, but for how long?" I sniff.

Rage squints at me. "What's that mean?"

I consider telling them what I've learned, about how we regress if we don't feed, that we're kept conscious purely to serve the whims of Dr. Cerveris and his mob, who can take our minds away from us anytime they please. But I don't think they'd thank me for enlightening them. Treat me to a beating, more likely, for being the bearer of bad news.

"Just leave me alone," I mutter, shouldering my way past Rage.

"She thinks she's better than us," Tiberius jeers. "She probably wants to spread joy and peace among the zombies. Are we savages, Becky? Should we be put down like rabid dogs?"

I ignore him, grab a file and set to work on my teeth - I wasn't allowed a file in the cell, so they've sprouted. The others toss a few insults my way but ease up when I don't bite back. I'm glad when they stop talking. It's as noisy in here as it was in my cell, but I can deal with that. Their raised voices, on the other hand, strike me like punches.

Mark slides over after a while and grins weakly. "They told me what happened," he whispers.

"And you think I'm a fool," I snap, laying the file aside. "You think I should have gone along with the rest of them, hacked off limbs, burned people alive - or burned them dead, or however the hell you want to phrase it."

Mark shrugs. "I can't see what the fuss is, but I wasn't there. I've never been there. I don't know what goes on, so I can't judge." He slumps beside me. "To be honest, I think anything would be better than my checkups. They're operating on me more and more. They're worried about my organs, but I don't know why. I don't feel any different."

Mark rubs his eyes and I'm stunned to see his fingers come away wet.

"I thought all of our tear ducts had dried up," I murmur, grabbing his gloved hand and studying the moisture suspiciously.

"They've given me new drops," he explains. "A side effect is that I produce liquid that looks like tears. They say my eyes will dry up completely without the new drops, that I'll go blind." He sighs unhappily.

"Sorry," I mumble. "That must be horrible."

He nods. "But they're hopeful the drops will work. And it's nice having wet eyes again. They used to sting before."

My eyes don't really pain me, but I guess we're all different.

Mark says the zom heads have been in a foul mood since they returned from the terminated experiment.

"They snap at me all the time, but at each other too. They won't admit it, but I think they're ashamed as well as angry. When you refused to harm the zombies, it made them think about how willingly they've gone along with everything. It was just the way things were. Nobody thought they had a choice, or that there was anything wrong with what they were doing. Now they've started to question what they've done."

"And they're blaming me for that," I snicker. "Nobody likes a smartarse who shakes things up. The world's a lot simpler if you don't think too much about it. I'd be mad too in their shoes. I didn't want to rock the boat. I just couldn't take it. I can't see the reviveds as monsters. They're still people in my eyes."

Mark gives my arm a squeeze. "Don't worry," he says. "They'll forgive you. Everyone's grumpy because of the diet, but once they give us back our regular rations, I'm sure - "

"What are you talking about?" I cut in sharply.

"They stopped feeding us a couple of days ago," he says, surprised by my tone.

"You mean after the others came back from the experiment?" I press.

"Yeah. They fed us the first day, same as normal, but nothing since."

I curse loudly and everyone looks at me. I start to get to my feet, to tell them of my suspicions, then pause and sit down again.

I might be wrong. Best not to say anything until I'm certain. I don't want to stir them up if there's no real reason for it.

So I keep my own counsel and sit out the shift, the hours dragging even slower than usual. When Reilly comes and takes us away, one by one, like he always does, I wait until he's leading me back to my cell, then grunt my question at him without looking around. "Are the others being starved because of what I did?"

"Yes," he says without hesitation. "It was Dr. Cerveris's idea. I don't like it, but my vote doesn't carry much weight round here."

"My fading eyesight... my improving sense of smell and hearing... that's part of the regression?"

"Yes," he says. "Reviveds rely on their nostrils and ears more than their eyes. The others haven't been denied food quite as long as you have, so they haven't deteriorated as much as you. But they'll start to notice a significant change within the next day or two."

"How long can we go without food before we turn completely?" I ask.

"It varies from one revitalized to another," he says evenly. "But nobody's ever lasted more than a week."

"Are the doctors serious about this? It's not a bluff?"

"Dr. Cerveris doesn't bluff," Reilly says with what sounds like a genuine sigh. "He doesn't need to. There are other revitalizeds he can turn to."

"So if I refuse to cooperate..."

I falter, so Reilly finishes the sentence for me. "... then they'll let Mark and all the other zom heads starve and turn back into brain-dead zombies."