It made no sense to try to stop a magician who had started down this path.

I was walking in the direction of the Economic Exhibition metro. I knew where it was all going to happen. Coincidences aren't coincidences when they're controlled by higher magicians. The absurd 'box on stilts', the matchbox standing on its end – that was where Zabulon had lost the battle for Svetlana, that was where Gesar had unmasked the Light Magician he'd assigned to the Inquisition, teaching Svetlana a lesson in the process.

The focus of power for the whole complex manoeuvre.

For the third time.

I didn't feel like eating or drinking, but I stopped once, bought a coffee and drank it. It was tasteless, as if all the caffeine had been filtered out of it. People started making way for me, even though I was walking in the ordinary world. The magical tension was rising.

There was no way I could conceal my approach.

But I didn't want to creep up on them anyway.

A pregnant woman was walking cautiously along the pavement. I shuddered when I saw she was smiling. And I almost turned away when I realised her unborn child was smiling too in its own safe little world.

Their power was like pale pink peonies – a large blossom and a round bud that hadn't unfolded yet.

I had to gather what I found along my way.

Without hesitation or pity.

There was something happening in the world around me too.

The heat seemed to have got stronger. In a single desperate surge.

The Dark and the Light Magicians must have had good reason to spend all those days trying to disperse the heat. Something was going to happen. I stopped and looked up at the sky through the Twilight.

Subtle, twisted coils of swirling air.

Sparks on the horizon.

Fading light in the south-east.

A glowing nimbus round the needle of the Ostankino TV Tower.

It was going to be a strange night.

I touched a little girl running by and took the naïve joy she felt because her father had come home sober. Like snapping off a briar branch, prickly and fragile.

Forgive me.

It was almost eleven o'clock when I reached the 'box on stilts'.

The last person I touched was a drunken factory worker, slumped against the wall in the alley. The same alley where I'd killed a Dark One for the first time. He was barely even conscious. But happy.

I took his power too. A dusty, trampled stem of coarse plantain, a crude, dirty-brown candle.

That was power too.

As I crossed the road, I realised I wasn't alone. I summoned my shadow and withdrew into the Twilight.

The building was cordoned off.

It was the oddest cordon I'd ever seen. Dark Ones and Light Ones all together. I spotted Semyon and nodded to him. He gave me a calm, slightly reproachful look. Tiger Cub, Bear, Ilya, Ignat . . .

When had they summoned them all? While I was wandering round the city, gathering power? Sorry about that holiday, guys.

And the Dark Ones. Even Alisa was there. The witch was a terrible sight: her face looked like a paper mask that had been crumpled and straightened out again. It looked as if Zabulon hadn't been lying when he told me she'd be punished. Alisher was standing beside Alisa, and when I caught his eye, I could tell the two of them would fight. Maybe not now. But some day.

I stepped through the ring.

'This is a restricted zone,' said Alisher.

'This is a restricted zone,' echoed Alisa.

'I have a right to enter.'

I had enough power in me to enter without permission. Only the Great Magicians could stop me now, but they weren't there.

They didn't try to stop me. Someone, either Gesar or Zabulon, or maybe both, must have ordered them just to warn me.

'Good luck,' I heard someone whisper behind me. I swung round and caught Tiger Cub's eye. I nodded.

The entrance hall was empty. And the house had gone quiet, like the time when the immense Inferno vortex was spinning over Svetlana's head: the Evil that she had summoned against herself.

I walked on through the grey gloom. The floor echoed hollowly under my feet. In the Twilight world even the ground responded to magic, even the shades of human buildings did.

The trapdoor to the roof was open. Nobody was trying to put any obstacles in my way. The trouble was I didn't know if I ought to be pleased about that.

I emerged from the Twilight. I couldn't see any point in it. Not now.

I started climbing the ladder.

The first person I saw was Maxim.

He looked quite different from the way he had before, the spontaneous Light Magician, the Maverick who had killed adepts of the Dark for years. Maybe they'd done something to him. Or maybe he'd just changed. There are some people who make ideal executioners.

Maxim had been lucky. He'd become an executioner. An Inquisitor. Standing over and above the Light and the Dark, serving everybody – and nobody. He had his arms crossed on his chest and his head slightly lowered. Something about him reminded me of Zabulon, the first time I'd seen him. And something reminded me of Gesar too. When I appeared, Maxim raised his head slightly and cast a casual glance at me. Then he lowered his gaze.

So I really was allowed in on the whole show.

Zabulon was standing to one side, wrapped in a pale raincoat. He took no notice of my arrival. He'd known I'd be there anyway.

Gesar, Svetlana and Egor were standing together. They gave me a much livelier reception.

'So you came after all?' the boss asked

I nodded and looked at Svetlana. She was wearing a long white dress and her hair was loose. She had a small, glittering box made of white morocco leather in her hand. It looked as if it was meant for a brooch or a medallion.

'Anton, so you know then?' Egor shouted.

If anybody there was happy, he was. Perfectly happy.

'Yes, I know,' I answered. I walked up to him and ruffled his hair.

His power was like a yellow dandelion.

Now I felt like I'd collected all I could.

'Full up?' asked Gesar. 'Anton, what are you planning to do?'

I didn't answer. Something was bothering me. There was something wrong here.

That was it! Why wasn't Olga there?

Had the final briefing already been given? Did Svetlana already know what she had to do?

'A piece of chalk,' I said. 'A little piece of chalk, pointed at both ends. You can use it to write on anything. In a Book of Destiny, for instance. Cross out old lines, write in new ones.'

'Anton, you're not going to tell anyone here anything they don't already know,' the boss said calmly.

'Has permission been given?' I asked.

Gesar looked at Maxim. As if he could feel the glance, the Inquisitor raised his head and said in a hollow voice:

'Permission has been given.'

'The Day Watch wishes to object,' Zabulon said in a dull voice.

'Denied,' Maxim replied indifferently and lowered his head back on to his chest.

'If a Great Sorceress picks up the chalk,' I said, 'every line in the Book of Destiny will take a particle of her soul. And return it to her, changed. You can only change a person's destiny by giving away your own soul.'

'I know,' said Sveta. She smiled. 'I'm sorry, Anton. I think this is the right thing to do. It will be good for everyone.'

There was a brief glint of concern in Egor's eyes. He'd sensed something was wrong.

'Anton, you're a warrior of the Watch,' said Gesar. 'If you have objections, you may speak.'

Objections? To what? To Egor becoming a Light Magician instead of a Dark one? To an attempt, even if it was bound to fail, to bring Good to humans? To Svetlana becoming a Great Sorceress?

Even at the cost of sacrificing everything human she still had inside her.

'There's nothing I wish to say,' I said.

Did I imagine it, or was there a flash of surprise in Gesar's eyes?

It was hard to tell what the Great Magician was really thinking.

'Let's begin,' he said. 'Svetlana, you know what you have to do.'

'I do,' she said, looking at me. I moved a few steps away from her. So did Gesar. Now there were just the two of them standing together – Svetlana and Egor. Both equally anxious. Equally tense. I looked across at Zabulon – he was waiting. Svetlana opened the little box – the click of the catch sounded like a gunshot – and slowly took out the piece of chalk, almost as if she didn't want to. It was tiny. Had it really been worn down so much by the Light's attempts to alter the destiny of the world over the millennia?

Gesar sighed.

Svetlana squatted down and began drawing a circle around herself and the boy.

I had nothing to say. I didn't know what to do.

I'd collected so much power that it was bursting out of me.

I had the right to do Good.

There was just one little thing missing – I didn't understand exactly how.

The wind stirred. Timidly, cautiously. Then it faded away.

I looked up and shuddered. Something was happening. Here, in the human world, the sky was covered with clouds. I hadn't even noticed them appear.

Svetlana finished drawing the circle and stood up.

I tried glancing at her through the Twilight and immediately turned away. She seemed to be holding a red-hot coal in her hand. Was she feeling any pain?

'There's a storm approaching,' Zabulon said from one side. 'A real storm, the kind we haven't had for a long time now.'

He laughed.

Nobody paid any attention. Except perhaps the wind – it started blowing more evenly, growing stronger. I looked down at the street – everything was calm. Svetlana was tracing the chalk through the air as if she was drawing something only she could see. A square outline with some design inside it.

Egor gave a quiet groan and threw his head back. I took half a step forward and stopped. I couldn't get across the barrier. And there was no point anyway.

When you don't know what to do, don't trust anything. Not your cool head, not your pure heart, not your hot hands.

'Anton!'

I looked at the boss. Gesar seemed worried.

'That's not just a storm, Anton. It's a hurricane. People will be killed.'

'The Dark Ones?' I asked simply.