'Nice.'

'It's not meant to be nice.'

'OK. So I slip in, deal with the guards and let you guys in. Then what? I go through the cut to the Council building and find Wallend, Soul and Jessica?'

'Precisely. But that brings us to the second problem: Jessica.'

Celia rubs her face with her hand, then says, 'Even if Soul, Wallend and the Council are defeated, the Hunters will still be against us. The Hunters do the bidding of the Council but they don't follow Soul; their true loyalty is only to their leader, to Jessica. While Jessica is alive, the Hunters will fight. Whatever has happened to Soul or Wallend, she'll never surrender.'

'And?'

'You let her live in Geneva,' Celia says.

I laugh. 'Oh. So the problem is that you think I won't kill her?'

'Is it a valid problem?'

'No.' At least I don't think it is. Jessica is my half-sister, the daughter of my mother, but I hate her. I do believe she's evil. And I know she'd kill me without a second thought. It's true I let her go in Geneva. But we weren't at war then. Things have changed, and I've changed too.

I tell Celia, 'Don't worry. I'll kill or capture her.'

Celia nods and moves swiftly on. 'Problem three is also to do with Hunters. There is a myth about them that they won't surrender or run ever. But, as you know, that isn't totally true. Many will die rather than surrender but the truth is that they are all human. Some will choose to live. And I think when they see that they can't win they will make a tactical withdrawal, and they may even surrender. If they do, then we don't harm them. The organization will need to be disbanded. We need to break the history of the Hunters.'

I remember my dream of a long line of Hunter prisoners.

'Executing them all would be a good way to do that.'

'No it wouldn't. Hunters come from virtually every family of White Witches. We need to show tolerance and fairness. They are soldiers. They aren't evil.'

I shake my head at Celia.

'We don't kill prisoners, Nathan. And we don't kill those who surrender.'

'So what exactly is the third problem?'

'Nathan, I need to be sure that you won't kill them if they've surrendered, and if they want to surrender you let them. I need to believe that you know it would be wrong to execute prisoners.'

'You mean you need to believe I'm not like my father. That I don't want revenge for my ancestors who were all killed by them. And what about all the other Black Witches who've been killed by Hunters? Can't I get a little revenge for them too?'

'I want us to win this battle, not get revenge.'

'"Kill them all" is my motto.'

'Even if they've surrendered? That makes you no better than Soul.'

'Yes ... No.' I'm not sure how I feel except that I'm pissed off. I sneer at her and say, 'You can try them all first for war crimes if that makes you feel any better. Then execute them.'

Celia says, 'My plan is to run the Alliance with Whites and Blacks and Half Bloods working together. We will have to investigate carefully and publicly the crimes that the Council and its members have committed. But we must all be careful not to commit similar ones. Or we too will be in the dock.

'We will work together and we will have to be, and be seen to be, fair to all. Just and fair. To all, including you, Nathan. I'm warning you that this will happen. That is the society that we need to establish and we all must be subject to the same rules. The battle is the easy bit; what comes after will be the real challenge.'

'Thanks,' I say. 'Glad everyone appreciates what a doddle of a job I've got on my hands.'

Celia says, 'So, back to our attack. Is the third problem a valid one?'

I tell her, 'My objective is to win the battle and remove, one way or the other, Soul and Wallend and Jessica. I'll kill anyone who gets in the way of that or who tries to kill me or any Alliance fighters. If we win and there are any Hunters or Council members alive, I'm going to leave them to you to sort out. You can sit in the Council building in meetings all day playing with your conscience; I'll be living quietly by a river.'

'And Annalise?'

'I won't forget my mission and go hunting her down. Wallend, Soul and Jessica are my priority.'

'If Annalise is alive she should go on trial as the Alliance originally planned.'

'Well, let's just hope she's been tortured to death by now.'

Celia doesn't respond to that so I say, 'The next problem?'

She starts to get up, saying, 'It's late; we'll go through them tomorrow. We all meet here first thing. There's one more thing you should know. I'm going to tell everyone about your invulnerability. It will give them confidence going into the fight.'

I think about it, but I don't suppose it'll make any difference to me what they know.

'Fine,' I say.

She takes a step away and then turns back to me. 'I suspect the major problem will be problem fifty-one, so don't be complacent with your new Gift.' And then she walks off to her tent.

I shake my head. I'm not feeling the least bit complacent.

'What's she talking about?' Gabriel asks. 'Problem fifty-one?'

I tell him, 'It's one of her things. She always used to say there were many problems in any battle and she could always come up with fifty things that could go wrong. Problem fifty-one was slightly different; it was always there, but even she couldn't think what it could be.'

never-ending problems.

The annual meeting of the Council is a big affair and will include the key Council members from Britain and possibly a few from Europe. But it's such an obvious target that it's bound to be well guarded. We can only hope that they think the Alliance is so weak and depleted it will be unable to attack.

Problem four is the date. The meeting is usually held on the last day of April but it would be typical of Soul to change this.

Problem five is the layout of the Council building, which is a labyrinth of corridors. I've been there every birthday from age eight to age fourteen but I've only seen a fraction of the building; even from my limited experience I realize it's vast and the corridors complex. Celia, Greatorex and some of the other members of the Alliance do know the building, or at least parts of it, and they've drawn up a plan from the cells in the basement to the attic rooms. There are some areas on the top floors that they don't know and of course they think that is where Wallend has his laboratory.

All the Alliance trainee fighters from Camps One to Seven are here now. There are more than I hoped but fewer than we need: twenty-seven. Most faces I don't recognize. We all spend time learning the layout of the building. The plan is for me to go in first and for the other members of the Alliance to come in only if I can remove the Hunters' invisibility and after I've killed or captured Soul. Greatorex keeps saying to the trainees, 'You must be able to find your way if it's dark and smoke-filled. You must know it better than any place you've ever been.' And that's true for me as well.

To help us learn the layout of the building, each floor has been marked out on the ground, and key areas have been replicated with walls made of wood and canvas. These are the basement, ground floor and top floor. The basement is where we will enter. The cut from the Tower goes in there, to make it easier to move prisoners between the cells and the Tower. The ground floor has all the main offices and meeting rooms, including Soul's private office.

They've been working on the replica while I've been away but when I go round it some things don't seem right to me. The stairs down to the basement should be narrower. I remember the guards had to push me ahead of them and it was really cramped.

I go into the replica of the cell that I was kept in. The walls are canvas and there's no roof. It's morning and the sky is blue above. I pace out the cell as I remember it. Where I was chained up, how far I could move along the wall. I walk out of the cell and go to Room 2C. This seems more like the real place; the canvas walls remind me of the white of the room. I lie down in it and remember Wallend bending over me, tattooing me. I wonder how many others he's done that to by now.

I wander around the whole cell area. Learning the layout but wondering, too, how many people they will be holding in each cell. Just one in solitary or twenty squeezed in with no space to lie down? I remember all the stories Celia used to read me about the gulags and the punishments and interrogations, and I'm sure they'll be making each place as bad as they can.

I sit in my old cell again, up against the wall in the corner where I sat the first night I was forced to stay indoors as my witch powers grew. I remember how sick I was, how frightened. I was sixteen, which sounds so young, but I'm only seventeen now and I realize that I was in the cell a year ago, less than a year ago. Shit, it feels like twenty years. And I've changed, experienced so much. Back then all I wanted was to escape and be given three gifts on my birthday; all I wanted was to live free. And here I am, and I've got my Gift and many more besides. I've got more power than I'd have thought possible and I'm risking it all. And yet I feel confident about the attack. I am invulnerable after all. I know we have a good chance. Soul and Wallend and Jessica will be there for sure. And Annalise, if she's still alive, may be down here somewhere, in this cell or a prisoner in the Tower. I tell myself that but I also know there's a chance she isn't a prisoner, isn't being tortured, but being kept in comfort because she shot Marcus, because she's a spy.

'I wondered where you were. It's getting late.' Gabriel comes and sits by me.

It's dark. The day's gone and the last few hours I've been lying here in the cell, thinking.

'What's bothering you?' Gabriel asks.

'You want the full list or just the top ten?'

I'm surprised that my voice is shaking. Saying it makes me realize how close to the edge I am. And I know soon I'm going to step off it completely.

Gabriel leans close to me, his voice quiet as he says, 'Give me the full list.'

'Am I bad for killing people? For wanting to kill them?'

'You have the power to fight. You do what other people can't do. You're not bad, Nathan. But do what you believe in; only do that. You have to live with your conscience. Only you can know what's in there and only you have to live with it.'

I rub my face in my hands. And I suddenly want my father back with me to help me.

'I never thought I'd kill people. A year ago I was being kept in this cell and I didn't want to kill anyone, not even the people who held me prisoner. I just wanted to escape, just wanted freedom. And now I have that; I have my freedom.'

'Do you? Sometimes I think you're still a prisoner. You're not free of this place in your head, Nathan. And you're definitely not free of those people. They haunt you.'

'Maybe. I dream about them a lot. Bad dreams. In my dream there's a long line of prisoners knelt on the floor, hands tied behind their backs. And when I say a long line I mean long, never-endingly long. And I walk behind them and I have a gun and I shoot each one in the back of the head. And as each one slumps to the ground I step forward and execute the next one.'

'And this is a dream? Not a vision?'

I shake my head. 'Visions feel different. This is a dream. But I hate it more than anything. I hear my father's voice telling me, Kill them all. Kill them all. And he's not angry or mad or anything like that: he's calm and logical, and he fills me with confidence that I can do it. And I know when I get to the end of the line I'll be able to stop, and my father will be quiet.' I look at Gabriel and say, 'But I never get to the end of the line. I'm never able to stop.'

'You have to stop at some point, Nathan, but because you choose to. You'll never kill them all. It's impossible. And ... I think it's wrong. I mean it's wrong for you. It's a path your father would have gone down, did go down. But you have to choose what is right for you. You aren't disrespecting your father by following your own path. He knew you loved him. He knows it still. You don't have to do this for him.'

I nod. I know Gabriel is right. Everything he says is right. But just now I feel more lost than ever.

He takes my hand and weaves his fingers with mine and says, 'You will stop, Nathan. I'll help you stop. And you will live a quiet life by your river and I'll be there with you.'

It's three days to the attack. We're all ready. Even the trainees look pretty good. Every day, Gabriel and I train together. For fitness we run and climb in the forest and then we practise in the Council building mock-up. We test each other in there. Trying to confuse each other, put each other off with noises, shots, but we know we've got it sussed. Today we're going to the Tower. I want to see it before the attack anyway but Celia is taking us there so we can find out the passwords.

Me, Celia and Gabriel go through a cut to London and make our way to a grim residential estate that is a wasteland of mud, sparse grass, litter and broken tarmac. There are five towers, each seemingly separate and unconnected to the others and anything else around them. Celia has already had someone check out the guards' movements but she wants me to check again, closer, using my invisibility.

Roman Tower looks nothing like a fain prison, at least not in the ordinary sense of the word: it's orange for a start. All five towers are seventies-style blocks, each one with its panels painted a different colour: red, yellow, orange, lime green and pale blue. The colours and the concrete are all dirtied and worn. Roman Tower is five storeys taller than the others and the prison occupies the top five floors. Below live ordinary fain residents. How or why they don't notice who lives above them I haven't asked. I guess it's a mixture of magic and general apathy.

The guards mostly live in the other towers, and they use the ordinary fain entrance to get to the prison. The Hunters get to work through the Council building, through the cut. In Celia's day there were six guards and four Hunters on each shift. The guards are not trained to fight, but the Hunters are Hunters. Each floor can house up to twenty prisoners, so there might be as many as a hundred in there.

Anyway, we're here to watch the guards and confirm their pattern of movement. I'm standing with Gabriel in the shelter of a building that's occupied by a series of shops and a launderette. All have their graffitied shutters down but even here the graffiti isn't up to much: like no one could really be bothered with that either. Gabriel is standing close to me. We're eating a takeaway curry, which isn't as disgusting as its green colour would suggest, but then any food is good food to us.

Celia is at the other end of the wasteland. The guards change over three times a day. We're waiting for the 4 p.m. changeover, or rather I'm waiting for it as it's only me that's going to go in. We've agreed I'll go into the Tower at three thirty and suss it out and most importantly suss out the entrance to the top five floors. Celia says that the entrance to the prison has an outer and an inner door. The first door is opened from the outside by the person saying the password and using a key and this leads to a holding area. The next door is opened from the inside, again with a key and a password. There's a peephole to check the incomers are who they are supposed to be. All I've got to do is shadow the guards as they go in, check that the system is still in place and find out what the password to the outer door is.

At three thirty, I set off, walking slowly across the expanse of open ground to the Tower. There's a number-code system to gain entry, but the door is broken anyway so I go straight in. There's a lift but I go up the stairs. In the stairwell the smell of stale urine is strong but the steps are clear of rubbish, just dirty with years of grime. I become invisible now and move silently and quickly. I check out each floor, looking for anything that might be out of place; any sign that Hunters are watching or setting a trap. I don't see anything and I don't get any feeling that Hunters are here or things are out of place.

On the eleventh floor there is only one door: the entrance to the prison. I realize I'm tense, holding my breath. I stand in the furthest corner, back against the wall, and concentrate on breathing slow and staying invisible while I wait for the guards.

It's not long before I hear the lift crank into gear. There's no lift door on this floor. It might be them or it might not. I find I'm holding my breath again. Then the lift doors open on the floor below and I hear footsteps coming up the stairs. No one talks. There're five of them but they're typical of the guards used in the Council building huge. Not dressed like guards or Hunters, though, but like fains, in jeans, jumpers and jackets.

When they're at the door to the prison, all I can see is the backs of five massive men. One of them says something 'Ring ray' it sounds like. Then the door opens and they move through into another room but I can't see much and the door shuts.

Shit, that was useless.

Now what?

Then I hear more footsteps on the stairs. They get louder and slower and finally another guard appears. The sixth one.

He goes to the door, puts a small key in the lock and leans to the hinged side, not the side that opens, and says, 'Spring day.' He has his left hand on the key and as he says the words he turns the key and the door opens. I get a brief look inside to a small room, painted in shiny orange paint with an orange door beyond it. Then the outer door closes.

I make my way back to Gabriel and Celia slowly, still checking each of the floors of the Tower again for anything that might feel out of place but I don't spot anything.

Celia seems pleased, if she ever seems pleased about anything. She says, 'The system is working the same as in the past. You'll be able to get in. Of course, once you're in you have to deal with the guards, et cetera, et cetera.'

I turn to Gabriel, saying, 'Et cetera, et cetera: that's my speciality.'

Celia replies, 'It'd better be.'

scum.

When we get back from our trip to the Tower, I go to the mock-up of the Council building. I know I have to keep practising and double-checking my knowledge of the layout, and it's reassuring to go over it again and again. It's night, so a good time to practise in the dark.

I'll get into the Council building through the cut in the basement, invisible, and I do that now: go invisible and go through the basement and its narrow corridors, then up to the ground floor and then up the main staircase to the fifth floor, the top floor. It's the place we know least about but I go through where I'll look for Wallend. Then I have to deal with Soul. And so now I make my way back through the corridors to Soul's private office on the ground floor, as I plan to do it: walking quiet and fast. This part of the mock-up re-creates the corridors, meeting rooms and offices with walls of tarpaulin across wooden frames.

There's a strong wind and the tarp is flapping and snapping. I slow as I get closer to Soul's office, looking and listening, imagining where guards would be positioned, staying invisible as I move past them. I'm almost at the doorway to Soul's office when I hear the voices of some trainees. Greatorex encourages them to practise constantly so I shouldn't be surprised they're here, but I don't want to go in there with them around. Anyway, I've done most of my route; I can start again from the beginning. I'm about to retrace my steps along the tarpaulin-lined corridor when I hear my name and I stop. I realize they're not practising but talking. I go back to listen.

'If he does manage to kill Soul, then this could all be over. Soon.'

'It's a big if.'

'Well, he's got more chance than anyone. And look on the bright side: if he fails at least he'll be killed.'

'He's invulnerable. He can't be killed.'