'Yes.'

He didn't want to involve the two Watches. Right now we were just Others. We might be on duty, we might be on assignment, but Zabulon preferred not to raise the conflict to the level of an official confrontation. Why? Was he so very confident of his own powers, or was he afraid the boss might turn up?

I didn't get any of it.

And the most important question of all was why he'd left our headquarters and abandoned the hunt for the sorcerer who'd put the curse on Svetlana. The Dark Ones had insisted that the sorcerer must be handed over to them. Why would he abandon that claim so easily?

What did Zabulon know that we didn't?

'Your pitiful—' the Dark Magician began. But before he could finish, the hostage made his move.

I heard Bear's puzzled growl of confusion and looked round.

After playing hostage in the vampire's clutches for the last half-hour, Egor was dissolving, disappearing.

The kid was withdrawing deeper into the Twilight.

The vampire squeezed her arms together in an attempt to keep hold of him ... or kill him. The sweeping movement of the clawed hand was swift, but it met no living flesh. The vampire struck herself under her left breast, in the heart.

What a pity she wasn't alive!

Like a snowdrift suddenly springing into life, Bear leapt, streaking through the empty air where Egor had just been standing and felling the vampire. The twitching body was completely covered by his massive form, with just one clawed hand protruding from under his shaggy side and twitching spasmodically.

In the same instant Ilya raised the wand. The lilac glow dimmed slightly, and then the wand exploded into a column of white flame. He looked as if he was holding a beam of light torn from the lamp of a lighthouse. It was blinding, I could almost feel its weight. With a visible effort, Ilya swung his arms, scraping the grey sky with a beam of light brighter than any seen in Moscow since the war, and swung the huge club down on Zabulon's head.

The Dark Magician cried out.

He fell, pinned down on to the roof, and the column of light tore itself out of Ilya's hands, moving of its own accord. It was no longer a beam of light, but a white snake, sprouting silvery scales as it coiled and writhed. The end of the gigantic body flattened out into a hood and a blunt head protruded from under it, with unblinking eyes the size of truck wheels. The slim, forked tongue flickered, blazing like a gas burner.

I jumped back as the tail almost caught me. The fiery cobra coiled itself into a ball and fell on Zabulon, rapidly winding the coils of its body round his head. And on the far side of the blazing coils three shadows thrashed away at each other, their rapid movements blurred into dim streaks. I hadn't noticed when Tiger Cub leaped at the witch and the warlock.

Ilya laughed quietly and took another wand from his belt. This one was less bright – he must have charged it himself.

Had he been carrying a weapon designed personally for Zabulon, then? Had the boss already known whom we'd be up against?

I looked round the roof. At first sight, everything was under control. Bear was lying on the vampire, with occasional muffled sounds emerging from beneath his body. Tiger Cub was dealing with the two Day Watch agents, and it didn't look as if she needed any help. The white cobra was throttling Zabulon.

We were left with nothing to do. Ilya was watching the struggle, holding the wand at the ready, evidently trying to decide which tussle to throw himself into. Semyon had never taken any interest in the Day Watch agents and Zabulon, and now he'd lost all interest in the vampire and was wandering along the edge of the roof, looking down. Was he worrying about new reinforcements for the Dark Side?

And I stood there like an idiot, holding the useless pistol in my hands. . .

My shadow sprang to my feet at the first attempt. I stepped into it, feeling the searing chill. Not the chill that humans know, not the chill that every Other knows – this was the chill of the deep Twilight. Here there was no wind, here the snow and ice under our feet had disappeared. Here there was no blue moss. The space was entirely filled with fog, thick and glutinous. If fog can be compared with milk, then this was curdled milk. My friends and enemies alike had all been transformed into vague shadows that were barely moving. Only the fiery cobra fighting with Zabulon was as fast and bright as ever – that battle was being fought at every level of the Twilight. Thinking about the amount of energy that must have been transferred to that wand made me feel dizzy.

But what for? Dark and Light, what for? Neither the vampire nor this young Other, the boy, were worth all this.

'Egor!' I shouted.

I was beginning to feel frozen. I'd only ever entered the second level of the Twilight twice: once in class, with an instructor beside me, and the day before, to get through the door of the apartment. I didn't carry any protection for this level, and every moment I was losing more and more strength.

'Egor!' I took a step through the fog. I could hear muffled blows behind me – the snake was pounding someone against the roof, clutching his body in its jaws . . . and I knew whose body . . .

Time down there moves even more slowly, and there was just a chance that the kid might not have lost consciousness yet. Struggling to make anything out in the gloom, I walked towards where he'd dived down to the second level of the Twilight, and I didn't see his body at my feet. I stumbled and fell, then got up, squatting on my haunches, and found myself face to face with Egor.

'You okay?' It was a stupid question to ask, because his eyes were open and he was looking at me.

'Yes.'

Our voices had a hollow, rumbling sound. There were two fluttering shadows right beside us: Bear was still struggling with the vampire. She was certainly holding in there for all she was worth.

And so was Egor.

'Let's go,' I said, reaching out and touching his shoulder. 'It's. . . tough being down here. We could get stuck here for ever.'

'So okay.'

'Don't you understand, Egor? To be dissolved in the Twilight means suffering, eternal suffering. You can't even imagine what it's like. We're leaving!'

'What for?'

'To stay alive.'

'What for?'

My fingers wouldn't bend. My pistol felt heavy, cast out of ice. I might last another minute, or two . . .

I looked into Egor's eyes.

'Everyone decides for himself. I'm leaving. I've got something to live for.'

'Why do you want to save me?' he asked curiously. 'Does your Night Watch need me?'

'I don't think you'll join our Watch,' I said, surprising even myself.

He smiled. A shadow slowly ran through us – Semyon. Had he spotted something? Was someone in trouble?

And there I was, wasting my final strength trying to prevent a little Other from committing esoteric suicide – when he was doomed anyway.

'I'm leaving,' I said. 'Goodbye.'

My shadow clutched hold of me, freezing to my fingers and growing on to my face. I began to tear myself away from it and the Twilight hissed at me.

'Help me!' said Egor. I only just caught the sound of his voice, I was almost out already. He'd left it right until the last moment.

I reached out and grabbed his hand. I was already being torn out, the fog around me was melting. All my help was purely psychological, the boy had to do the real work for himself.

And he did.

We tumbled out into the upper level of the Twilight. The cold wind struck me in the face, but this time it felt good. The listless movements on every side were transformed into a furious struggle. The blurred grey looked bright and colourful.

Something had changed during those few seconds we'd been talking. The vampire was still twitching under Bear . . . that wasn't it. The young warlock was lying on the roof, either dead or unconscious, Tiger Cub and the witch were struggling nearby . . . that wasn't it.

The snake.

The white cobra was expanding, inflating, filling a quarter of the roof. As if it had been pumped full of air and was rising, or flying up of its own accord into the low sky. Semyon was standing by the twined coils of its fiery body, half squatting in an ancient combat stance, with small orange spheres streaking from his palms into the clump of white flame. He wasn't aiming at the cobra, but at someone else beneath it, someone who should have been dead a long time ago, but was still struggling . . .

Then a sudden explosion!

A vortex of Light and scraps of Dark. I was tossed on to my back and as I fell I hit Egor and knocked him down, but I just managed to grab his hand. Tiger Cub and the witch, locked together, shot across to the edge of the roof and froze against the barrier. Bear was torn off the vampire, who was badly mauled but still alive. Semyon staggered, but remained on his feet, protected by a dimly glowing defensive shield. The only thing blown off the roof was the unconscious warlock: on his way he broke through the rusty bars of the barrier and plunged to earth in a helpless bundle.

But Ilya just carried on standing where he had been, rooted to the spot. I couldn't see any defences around him, but he just gazed curiously at what was going on, clutching his wand.

The remains of the fiery cobra soared upwards, spreading out into glowing clouds, melting away, scattering in showers of sparks and needle rays of light. Beneath this firework display Zabulon slowly rose to his feet, extending his arms in some complex magical pass. He'd lost his clothes in the struggle and was now completely naked. His body had changed, assuming the classic features of a demon: dull scales instead of skin, an irregular skull, covered with some kind of matted fur instead of hair, close-set eyes with vertical slits for pupils, a massive penis, and a short forked tail that hung from the base of his spine.

'Begone!' cried Zabulon. 'Begone!'

What must have been going on at that moment in the human world . . . Outbreaks of vicious depression and blind, irrational joy, heart attacks, bizarre behaviour, quarrels between best friends, betrayals by faithful lovers . . . People couldn't see what was happening, yet it touched their souls.

But why?

Why did the Day Watch want all this?

And at that moment I suddenly felt calm. A state of icy, rational composure I'd almost forgotten.

It was all one complex manoeuvre. If we started from one simple idea, made one initial assumption – that everything was happening according to the Day Watch's plan – and then connected up all the seemingly random events, starting with my hunt in the metro – no, starting with the moment when the young vampire had been allocated a girl to feed on, a girl he couldn't help falling in love with . . .

My thoughts were moving as fast as if I was acting as a brainstorm conductor, connected up to other people's minds, the way our analysts sometimes worked. But no, of course, that wasn't really happening, it was just that the pieces of the jigsaw had started moving around on the table in front of me, coming together.

The Day Watch didn't give a damn about the girl vampire . . .

The Day Watch wouldn't risk open conflict for the sake of a kid with potentially great powers. The Day Watch had only one reason for doing all this.

A Dark Magician of extraordinary power.

A Dark Magician who could reinforce their position, not only in Moscow, but right across the continent . . .

But then they'd already achieved that goal, we'd promised to hand over the Dark Magician . . .