Bear shifted forward slightly. A tiny movement, as if he hadn't shifted his powerful paws at all, just slipped when the wind pushed him. I knew he'd carry on sliding forward like that for another ten minutes, the same way he'd been doing for an entire hour since the stand-off began. Until he thought he had a good enough chance. Then he'd pounce . . . and if he was lucky, he'd be able to tear the kid out of the vampire's arms with no more harm done than a couple of broken ribs.

'We can't keep track of everybody,' I said. 'It's just not possible.'

This was terrible ... I was starting to feel sorry for her. Not for the boy who'd been caught up in the game played between Light and Dark, not for young Svetlana, with the curse hanging over her, not for the innocent city that would bear the full brunt of that curse ... I was feeling sorry for the vampire. It was a good question – where were we that night? The ones who call ourselves the Night Watch . . .

'In any case you still had a choice,' I said. 'And don't tell me you didn't. Initiation can only take place by mutual consent. You could have died. Died honestly. As a human being.'

'Honestly?' The vampire shook her head, scattering her hair across her shoulders. Where was Semyon? . . . How hard could it be to climb to the roof of a twelve-storey building? 'It would have been good to die – honestly. But the person who signed the licence . . . the one who earmarked me as food. Was he acting honestly?'

Light and Dark . . .

She wasn't simply the victim of a vampire on the rampage. She'd been marked down as prey, chosen by a blind throw of the dice. She had been destined to give up her life for the continuation of someone else's death. But that young guy who had crumbled into a heap of dust at my feet when he was incinerated by the seal had fallen in love with her. Really fallen in love . . . and he hadn't completely sucked out the girl's life, he'd turned her into his equal.

The dead can do more than tear off heads, they can fall in love too. The trouble is that even their love requires blood.

He'd had no choice but to conceal her, since he'd turned the girl into a vampire illegally. He'd needed to feed her, and only live blood would do for that, not the bottled blood of naïve donors.

So he'd started poaching on the streets of Moscow, and then we'd started to pay attention, the keepers of the Light, the valiant Night Watch, who hand victims over to the Dark Ones.

In a war the most dangerous thing is to understand the enemy. To understand is to forgive. And we have no right to do that – we never have had, not since the creation of the world.

'Even so, you still had a choice,' I said. 'You did. Someone else's betrayal is no excuse for your own.'

She laughed quietly.

'Yes, yes . . . good servant of the Light . . . Of course. You're right. And you can tell me a thousand times that I'm dead. That my soul has burned away and evaporated into the Twilight. But if I'm so malevolent, can you explain to me what the difference is between us? Explain that. . . make me believe it.'

The vampire lowered her head and looked into Egor's face. She spoke in an intimate, almost friendly tone:

'And you, boy, do you understand me? Answer me. Answer me honestly, don't take any notice of . . . my claws. I won't take offence.'

Bear made another tiny movement forward. I could feel his muscles tensing as he prepared to leap.

But then Semyon appeared behind the vampire, without a sound, with a movement that was smooth and quick at the same time – how did he manage to move that fast in the human world?

'Wake up, little one!' the vampire said encouragingly. 'Answer! Only honestly! And if you think he's right and I'm wrong ... if you really believe that... I'll let you go.'

I caught Egor's eye.

And I knew what he was going to say.

'You're right too.'

A cold, empty feeling. No strength left for emotions. Let them show on the outside, let them blaze like a bonfire that people couldn't see.

'What do you want?' I asked. 'To exist? All right . . . give yourself up. There'll be a trial, a joint court of the Watches.'

The girl vampire looked at me and shook her head:

'No, I don't trust your court. Not the Night Watch or the Day Watch.'

'Then why did you call me here?' I asked. Semyon was moving towards the vampire, getting closer . . .

'For vengeance,' she said simply. 'You killed my friend. I'm going to kill yours . . . while you watch. And then . . . I'm going to try ... to kill you. But even if I fail. . .' She smiled. '. . . you'll always know you didn't save the boy. Won't you, Watchman? You sign those licences without thinking about real people. And the moment you do look . . . out creeps your morality . . . your rotten, false, cheap morality. . .'

Semyon leapt.

And Bear leapt at the same time.

It was beautiful, and it was faster than any bullet or any spell, because in the end all that's left is the body striking the blow and the skill acquired over twenty, forty, a hundred years . . .

But I still pulled the pistol out from behind me and jerked the trigger, knowing that the bullet would fly through the air slowly and lazily, like a 'high-speed' shot from a cheap action movie, still leaving the vampire a chance to dodge, a chance to kill.

Semyon flattened out in the air, as if he'd hit a wall of glass, and slid down an invisible barrier, shifting into the Twilight as he went. Bear was flung off to one side – and he was far bigger. The bullet, crawling towards the vampire with all the grace of a dragonfly, flared up in a bright petal of flame and disappeared.

If it wasn't for the way the vampire's eyes were opening wider and wider, I might have thought she'd conjured up the protective shield herself. But that's something only the most powerful magicians can do.

'They are under my protection .. .' a voice said behind my back.

I swung round – and met Zabulon's gaze.

It was amazing that the vampire didn't panic. It was amazing she didn't kill Egor. The unsuccessful attack and the sudden appearance of the Dark Magician must have been much more of a surprise to her than to us, because I'd been half expecting something of the kind from the moment I took off the amulet.

I wasn't surprised he'd got there so fast. The Dark Ones have their own pathways. But why had Zabulon, the observer from the Dark Side, preferred this little tussle to staying in our headquarters? Had he lost interest in Svetlana and the vortex hanging over her head? Did he know something that we had no way of figuring out?

That wretched habit of trying to work everything out in advance! The field operatives had it beaten out of them by the very nature of their work, which was all instant response to danger, battle, victory or defeat.

Ilya had taken out his wand. Its pale lilac glow was too bright for a third-grade magician and too steady for me to believe he could have charged it. The boss had probably charged it himself.

So he must have been expecting something.

He must have been expecting someone to turn up with powers that matched his own.

Neither Tiger Cub nor Bear changed their form. Their magic didn't require any external devices, and certainly not human bodies. Bear kept his eyes fixed on the vampire, totally ignoring Zabulon. Tiger Cub stood beside me. Semyon walked slowly round the vampire, rubbing his waist and deliberately making sure she saw him. He left the Dark Magician to us too.

'They?' Tiger Cub growled.

It took me a moment to realise what was bothering her.

'They are under my protection,' Zabulon repeated. The magician was wrapped in a shapeless black coat and his head was covered with a crumpled beret of dark fur. He had his hands in his pockets, but somehow I was certain there was nothing there, no amulets, no guns.

'Who are you?' screeched the girl vampire. 'Who are you?'

'Your protector and mentor,' said Zabulon, looking at me. Not even straight at me, more a casual glance past me. 'Your master.'

Had he gone insane? The girl vampire had no idea of the balance of forces here. She was wound up, ready to blow. She had been prepared to die ... to end her existence. Now she suddenly had a chance to survive, but the way he spoke . . .

'I have no master!' The girl whose life depended on other people's death laughed. 'Whoever you are – from the Light, or from the Dark – remember that! I have no master and never will!'

She began backing away towards the edge of the roof, dragging Egor after her. Still clutching him with one arm, holding the other hand at his throat. A hostage ... a good move against the forces of Light.

And maybe against the forces of Dark too?

'Zabulon, we accept,' I said, laying my hand on the tense muscles of Tiger Cub's back. 'She is yours. Take her – until the trial. We honour the Treaty.'

'I am taking them,' said Zabulon, gazing forward blindly. The wind was lashing into his face, but the magician's unblinking eyes remained wide open, as if they were made of glass. 'The woman and the boy are ours.'

'No. Only the vampire.'

He finally deigned to look at me.

'Agent of the Light, I am only taking what is mine. I honour the Great Treaty. The woman and the boy are ours.'

'You are stronger than any of us,' I said, 'but you are alone, Zabulon.'

The Dark Magician shook his head and smiled in mournful sympathy.

'No, Anton Gorodetsky.'

They came out from behind the lift shaft, a young man and a young woman. I knew them. Oh yes, I knew them.

Alisa and Pyotr. The witch and the warlock from Day Watch.

'Egor!' Zabulon said in a quiet voice. 'Have you understood the difference between us? Which side do you choose?'

The boy didn't answer. But perhaps only because the vampire's claws were pressed against his neck.

'Have we got a problem here?' Tiger Cub asked in a purring voice.

'Uhuh,' I confirmed.

'Your decision?' asked Zabulon. His Watch agents weren't saying anything yet, keeping out of it.

'I don't like this,' said Tiger Cub. She edged a little closer to Zabulon and her tail lashed me mercilessly across one knee. 'I don't like the Day Watch's view of what's going on here . . . not one bit.'

Bear obviously shared her opinion: when they worked as a pair, one of them spoke for both. I looked at Ilya: he was twirling the wand in his fingers, smiling darkly as if he was thinking. Like a child who's brought a loaded Uzi to a party instead of a plastic machine gun. Semyon was clearly up for anything. He didn't give a damn about petty details. He'd spent seventy years running over rooftops.

'Zabulon, do you speak for the Day Watch?' I asked.

I saw a brief flicker of doubt in the Dark Magician's eyes.

What was going on? Why had Zabulon left our headquarters, abandoning the chance to track down an unknown magician of incredible power and enlist him in the Day Watch? You didn't just abandon an opportunity like that, not even for a vampire and a kid with potentially great powers. Why was Zabulon determined to go head to head?

And why on earth was he so reluctant – I could sense it, there was no doubt about it – to speak in the name of the Day Watch?

'I speak as a private individual,' said Zabulon.

'Then we have a few little personal disagreements,' I answered.