Zabulon laughed and raised his hands in the air.

'Anton, I'm not trying to coax any secrets out of you. I'm not going to ask any questions. Or ask you to do anything. Just listen to what I have to say. And then I'll go.'

I suddenly remembered how the young witch Alisa had used her right to intervene up on the high-rise roof the previous winter. A very minor intervention – all she did was allow me to speak the truth. And that truth had turned Egor over to the side of the Dark Ones.

Why did things happen that way?

Why was it that the Light acted through lies, and the Dark acted through the truth? Why was it that our truth proved powerless, but lies were effective? And why was the Dark able to manage perfectly well with the truth in order to do Evil? Whose nature was responsible, humankind's or ours?

'Svetlana's a wonderful sorceress,' said Zabulon. 'But her future is not to lead the Night Watch. They intend to use her for just one single purpose. For the mission that Olga failed to complete. You know, don't you, that a courier from Samarkand entered the city illegally this morning?'

'Yes, I know,' I admitted, without really knowing why.

'And I can tell you what he brought with him. Would you like to know?'

I gritted my teeth.

'You would,' said Zabulon, with a nod. 'The courier brought a piece of chalk.'

Never believe what the Dark Ones say. But somehow I got the feeling he wasn't lying.

'A little piece of chalk.' The Dark Magician smiled. 'You could write on a school blackboard with it. Or draw hopscotch squares on the pavement. Or chalk your pool cue with it. You could do all that, just as easily as you could use a large royal seal to crack nuts. But things change if a Great Sorceress picks up that piece of chalk – it has to be a Great One, an ordinary sorceress wouldn't be powerful enough, and it has to be a sorceress, in male hands the chalk remains nothing but chalk. And in addition to that the sorceress has to be a Light One. This artefact is useless for Dark Ones.'

Did I imagine it, or had he just sighed? I said nothing.

'A small piece of chalk.' Zabulon leaned back in his armchair. 'It's already worn down, beautiful young women with bright fire in their eyes have picked it up in their slim fingers several times already. It has been put to use, and the earth has trembled, the boundaries of states have melted away, empires have risen, shepherds have become prophets and carpenters have become gods, foundlings have been recognised as kings, sergeants have risen to become emperors, seminarians who failed to graduate and talentless artists have become tyrants. A little stub of chalk. Nothing more than that.'

Zabulon stood and spread his hands in a conclusive gesture.

'And that's all I wanted to tell you, my dear enemy. You'll understand the rest for yourself – if you really want to, that is.'

'Zabulon.' I unclenched my fist and looked at the amulet. 'You're a creature of the Dark.'

'Of course. But only of the darkness that was in me. The darkness that I chose myself.'

'Even your truth works Evil.'

'To whom? The Night Watch? Of course. But to humans? There I must beg to differ.'

He walked towards the door.

'Zabulon,' I said, calling him by name again. 'I've seen your true appearance. I know who you are and what you are.'

The Dark Magician stopped in his tracks. He slowly turned round and passed his hand over his face – for a moment it was distorted, the skin was replaced by dull scales and the eyes became narrow slits.

Then the illusion was dispersed.

'Yes. Of course you've seen it,' said Zabulon, in his human form once again. 'And I have seen you. And let me say that you were no white angel with a gleaming sword. Everything depends on the point you look from. Goodbye, Anton. Believe me, I shall be glad to eliminate you some time in the future. But for now I wish you good luck. From the depths of the soul that I don't have.'

The door slammed behind him.

And immediately, as if it had just woken up, the sentry system howled out of the Twilight. The mask of Chkhoen on the wall twisted into a ferocious scowl, with fury glinting in the wooden gashes of its eyes.

My security guards . . .

I silenced the system with two passes and hurled the freeze that I'd prepared at the mask. The spell had come in useful after all.

'A little piece of chalk,' I said.

I'd heard something like that before. But it was a very long time ago, and I hadn't really been paying attention. It could have been a few phrases thrown out by one of my tutors at a lecture, or idle social gossip, or a student myth. But there definitely had been something about a piece of chalk . . .

I got up off the sofa, raised my hand in the air and threw the amulet on to the floor.

'Gesar!' I called through the Twilight. 'Gesar, answer me!'

My shadow shot up towards me from the floor, took hold of my body and sucked me into itself. The light dimmed, the room swayed, the outlines of the furniture blurred. It was suddenly unbearably quiet. The heat had receded. I stood there with my arms thrown out wide as the greedy Twilight drank my power.

'Gesar, by your name I summon you!'

Threads of grey mist drifted through the room. I couldn't give a damn who else might be able to hear me shouting.

'Gesar, my mentor, I call on you – will you answer?'

Far away in the distance an invisible shadow sighed.

'I hear you, Anton.'

'Answer me!'

'What question do you want the answer to?'

'Zabulon – did he lie to me?'

'No.'

'Gesar, stop!'

'It's too late, Anton. Everything's going the way it's supposed to go. Trust me.'

'Gesar, stop!'

'You have no right to make any demands.'

'No right! If we are part of the Light, if we do Good, then I have every right!'

The boss didn't answer straight away. I even thought he'd decided not to say anything else to me.

'All right. I'll be waiting for you in an hour at the Para Bar.'

'Where?'

'The Parachutists' Bar. Near Turgenevskaya metro station, behind the old central post office.'

Then there was silence.

I took a step backwards, out of the Twilight. It was an odd sort of place to meet. Was that where Gesar had had his showdown with the Day Watch? No, that was supposed to have been in some restaurant.

Okay, what did it matter – the Para Bar, Rosie O'Grady's, even the Chance Club? It wasn't important. Parachutists, yuppies, gays, who cared?

But there was one other thing I had to find out before I met Gesar.

I took out my phone and dialled Svetlana's number. She answered immediately.

'Hi,' I said simply. 'Are you at the dacha?'

'No.' She seemed startled by my brisk, businesslike tone. 'I'm on my way into town.'

'Who with?'

She paused.

'With Ignat.'

'Good,' I said, quite sincerely. 'Listen, do you know anything about chalk?'

'About what?'

This time the puzzlement was obvious.

'About the magical properties of chalk. Have they taught you anything about its uses in magic?'

'No, Anton. Are you sure you're all right?'

'I'm better than that.'

'Has something happened?'

'Nothing special.'

'Do you want me . . .' She hesitated. 'Do you want me to ask Olya?'

'Is she there with you as well?'

'Yes, the three of us are coming back into town together.'

'I don't think so. Thanks.'

'Anton . . .'

'What?'

I walked over to the desk and opened the drawer with all my magical junk. I looked at the dull crystals, at the clumsily carved wand from the time when I still wanted to be a combat magician. I pushed the drawer back.

'Forgive me.'

'There's nothing I need to forgive you for, Sveta.'

'Can I come round to your place?'

'How far away are you?'

'Halfway there.'

I shook my head and answered:

'Not now, I've got an important meeting. I'll call you back later.'

I ended the call and smiled. Very often the truth can be malicious and false. For instance, when you only tell half the truth. Like telling someone you can't talk to them without explaining why.

Permit me to do Good through Evil. I don't have any other way right now.

Just to be sure, I walked round the apartment, looking into the bedroom, the bathroom and the kitchen. As far as I was able to tell, Zabulon really hadn't left any 'presents' behind him.

I went back into the study, switched on my laptop and inserted the disk with the general magic database. Typed in the password. Typed in the word 'chalk'.

I hadn't been expecting anything special to come up. What I wanted to know could easily require such a high security clearance that it had never been included in any data bases.

There were three entries for 'chalk'.

The first was a reference to a chalk quarry where a first-grade Light Magician and a first-grade Dark Magician fought a duel in the fifteenth century. Both of them died of simple exhaustion of their powers – they didn't have enough strength left to emerge from the Twilight at the end of the duel. During the following five hundred years almost three thousand people had died at the site.

The second entry referred to the use of chalk for drawing magical symbols and protective circles. There was a lot more information here, and I read through it all quickly. There was nothing of interest. Using chalk has no particular advantages over charcoal, pencil, blood or oil paint. Except maybe that it is easier to erase.

The third reference came in the section 'Myths and Unconfirmed Data'. Of course, this section was full of rubbish like the use of silver and garlic in fighting vampires, or descriptions of non-existent ceremonies and rituals.

But I'd come across times before when genuine information had been completely forgotten and hidden away among the myths.

Chalk was mentioned in the article 'The Books of Fate'.

I read halfway through it and realised I'd hit the bull's eye. The information was just lying there in full view, accessible to any novice magician – it might even be available in sources that were open to ordinary humans.

The Books of Fate. Chalk.