I don't see much of Dad over the next few days. It's like he's avoiding me. I want to ask him about the strange visitor, find out his real name, where he's from, why he was here, why Dad told him about my dreams. But Dad clearly doesn't want to discuss it, and what Dad wants, Dad gets.

So I say nothing. I keep my questions to myself. And I try to pretend that my surreal conversation with Owl Man never happened.

On Friday we visit the Imperial War Museum. I've been looking forward to this for weeks and my spirits lift for the first time since my run-in with Nancy and the rest of that bizarre afternoon. We don't go on many school trips - the money isn't there, plus we're buggers to control when we're let loose. Twenty of our lot were taken to the Tate Modern last year and they ran wild. The teachers swore never again, but they seem to have had a change of heart.

"I don't expect you to behave like good little boys and girls," Burke says on the Tube, to a chorus of jeers and whistles. "But don't piss me off. I'm in charge of you and I'll be held accountable if you get out of hand. Don't steal, don't beat up the staff, and be back at the meeting point at the arranged time."

"Do we get a prize if we do all that, sir?" Trev asks.

"No," Burke says. "You get my respect."

I love the War Museum. I was here before, when I was in primary school. We were meant to be looking at the World War I stuff, but the tanks and planes in the main hall are what I most remember.

"Look at the bloody cannons!" Elephant gasps as we enter the gardens outside the museum. "They're massive!"

"You can have a proper look at them later," Burke says.

"Aw, sir, just a quick look now," Elephant pleads.

Burke says nothing, just pushes on, and we follow.

The main hall still impresses. I thought it might be disappointing this time, but the tanks and planes are as cool as ever. The planes hang from the ceiling, loads of them, and the ceiling's three or four floors high. Everyone coos, necks craned, then we hurry to the tanks. They're amazing, and you can even crawl into some and pretend that you're driving them. We should be too old for that sort of stuff, but it's like we slip back to when we were ten years old - the lure of the tanks is impossible to resist.

Burke gives us a few minutes to mess around. We're the second group from the school to arrive. As the third lot trickle in, we form a group and head upstairs to where the Holocaust exhibition starts.

This is the reason we're here. We haven't focused much on the Holocaust in class - at least not that I remember, though I guess I could have slept through it - but our teachers reckon this is important, so they've brought us anyway, regardless of the very real risk that we might start a riot and wreck the place.

Burke stops us just before we go in and makes sure we're all together.

Kray sniffs the air and makes a face. "Something's burning."

I expect Burke to have a go at him, but to my shock it's Jonesenzio - I didn't even know he was here - who speaks up.

"One of my uncles was Polish. He was sent to Auschwitz in the thirties. Not the death camp, where they gassed people, but the concentration camp. He was worked like a slave until he was a skeleton. Starved. Tortured. The bones in one of his feet were smashed with a hammer. He survived for a long time, longer than most. But in the end he was hung for allegedly stealing food from a guard. They let him hang for nearly ten minutes, without killing him. Then they took him down, let him recover, and hung him again until he was dead."

Jonesenzio steps up to Kray, stares at him until he looks away, then says softly but loud enough for everyone to hear, "If there are any more jokes, or if you take one step out of line from this point on, you'll have to answer to me."

It should be funny - pitiful even - but it isn't. Everyone shuts up, and for the first time that I can ever remember, we stay shut up.

The exhibition is horrible. It's not so bad at the start, a bit boring even, where we learn about the buildup to war, how the Nazis came to power, why nobody liked the Jews. But it soon becomes a nightmare as we dip further into the world of ghettos, death camps and gas chambers.

Old film footage of Jews being rounded up and chased by Nazis hits hard. So does the funeral cart on which piles of corpses were wheeled to mass graves. And the rows of shoes and glasses, taken from people before they were gassed and cremated.

But what unsettles me most is a small book. It belonged to a girl, my sort of age. She wrote stories in it and drew sweet, colorful pictures. As I stare at it I think, That could have been me. Sitting in my room, writing and drawing. Then dragged out, shipped off to a death camp in a train, shaved bare, stripped naked, gassed, cremated or buried in an unmarked grave with a load of strangers. And all that's left of me is a stupid book I used to scribble in, in a cold, empty room where no one lives anymore.

Some of the others cry as we walk through the chambers of atrocity. I don't. But I feel my throat tighten and I have to look away more than once and blink until I'm sure my eyes are going to stay dry.

Coming out of the exhibition is like emerging into sunlight after being in a dark tunnel. The museum doesn't look so much like an adventure park now. The planes and tanks, the cannons, guns and swords that lie scattered around the place... They were used to kill people. Not actors, like in the movies. But real people like me and my mum. Like that little girl.

"Sobering stuff, isn't it?" Burke says to a few of us standing silently nearby.

"They were monsters," I growl.

Burke raises an eyebrow. "You think so?"

"Nobody human could have done that."

Burke shrugs, then leans in and whispers so that only I can hear, "Maybe that's what we should do with the immigrants."

I gasp and draw back from him, shocked.

Burke raises an eyebrow. "You look surprised."

"You can't say things like that!" I protest.

"Why not?" As I stare at him, he says, "I heard about your fight with Nancy and how Mrs. Reed white washed it because of her friendship with your father."

"How do you know about that?" I growl.

"It's no big secret," he says. "Aren't the gas chambers where it will all end if the likes of Mrs. Reed and your father get their way?"

"No!" I shout, then lower my voice when the others look at me strangely. "How can you even suggest that?"

"Because it's true," he snaps. "This is where hatred and intolerance lead. Don't be a child, B, and don't act like you're naive."

"You're wrong, they just want a society where - "

"Don't," Burke stops me. "I've heard all the arguments before. I'm not going to tell you which side you should be on. You're old enough to choose. All I'm saying is be aware. Know what you're signing up for and accept the consequences. Mrs. Reed and your dad are modern-day fascists. Only a fool would think otherwise."

Then he walks off and leaves me trembling.

I think about the Nazis. I think about my dad.

"It's not true," I whisper. "They're not the same."

But a voice inside my head snickers slyly and asks the question that I don't dare form out loud. Aren't they?