'Why can't you just watch over me?' I muttered, and then the phone started screeching again. I paced around the room until I found the receiver.

'Anton, was there something you wanted to say to me?' the disembodied voice asked.

'Not a thing,' I said sullenly.

'I see. Now add "glad to serve, your honour" to that.'

'I'm not glad. And there's nothing to be done about it. . . your honour.'

The boss paused for a moment.

'Anton, I really would like you to take this situation we have on our hands a bit more seriously. All right? I expect you to report back in the morning, in any case. And . . . good luck.'

I didn't exactly feel ashamed. But I wasn't feeling quite so irritated any more. I put my mobile phone in my jacket pocket, opened the cupboard in the hallway and wondered for a while what I ought to take to round out my kit. I had a few novel items of equipment that friends had given me the previous week. But I settled on the usual lot anyway – it's fairly compact and gives pretty good all-round coverage.

Plus the minidisc walkman. I don't need my sense of hearing for anything, and boredom is an implacable enemy.

Before I went out I took a long look at the staircase through the spy-hole. Nobody there.

And that was the beginning of one more night.

I rode the metro for about six hours, switching aimlessly from line to line without any system, sometimes dozing, letting my conscious mind take a break and my senses roam. There was nothing going down. Well, I did see a few interesting things, but they were all utterly ordinary, tame beginner's stuff. It wasn't until about eleven, as the metro got less crowded, that things changed.

I was sitting there with my eyes closed, listening to Manfredini's Fifth Symphony for the third time that evening. The minidisc in the player was totally wild; a personal selection, medieval Italian composers and Bach alternating with the rock group Alisa, Richie Blackmore and Picnic. It's always interesting to see which music comes up for which event. Today it was Manfredini.

I felt this sudden cramp — all the way up from my toes to the back of my head. I even hissed as I opened my eyes and glanced round the carriage.

I picked the girl out straight away.

Very pretty, young. In a stylish fur coat, with a little handbag and a book in her hands. And with a black vortex spinning above her head like I hadn't seen for at least three years.

I suppose the look I gave her must have made me look insane. The girl sensed it, glanced back at me and immediately turned away.

Try looking up instead!

No, of course she's not going to see the twister anyway. The most she could possibly feel is a slight sensation of alarm. And she can't get any more than the vaguest glimpse of that flickering above her head, out of the corner of her eye . . . like a swarm of midges swirling round and round, like the air trembling above the tarmac on a hot day . . .

She can't see a thing. Not a thing. And she'll go on living for another day or two, until she misses her step on the black ice, falls and bangs her head so hard it kills her. Or ends up under a car. Or runs into a thug's knife in the hallway, a thug who has no real idea why he's killing this girl. And everyone will say: 'She was so young, with her whole life ahead of her, everybody loved her . . .'

Yes. Of course. I believe it, she's a very good person, kind. There's weariness there, but no bitterness or spite. When you're with a girl like that you feel like a different person. You try to be better, and that's a strain. Men prefer to be friends with her kind, flirt a bit, share confidences. Men don't often fall in love with girls like that, but everybody loves them.

Apart from one person, who's hired a Dark Magician.

A black vortex is actually fairly ordinary. If I looked closely, I could make out another five or six hanging above other passengers' heads. But they were all blurred and pale, barely even spinning. The results of perfectly standard, non-professional curses. Someone had simply yelled after someone else: 'I hope you die, you bastard.' Someone had put it even more simply and forcefully: 'Go to hell, will you?' And a little black whirlwind had moved over from the Dark Side, draining good fortune and sucking up energy.

But an ordinary, amateurish, formless curse lasts no more than an hour or two, twenty-four hours at most. And its consequences may be unpleasant, but they're not fatal. That black twister hanging over the girl was the genuine article, stabilised and set in motion by an experienced magician. The girl didn't know it yet, but she was already dead.

I automatically reached for my pocket, then remembered where I was and frowned. Why don't mobile phones work in the metro? Don't the people who have them ride underground?

Now I was torn between my principal assignment, which I had to carry through, even with no hope of success, and the doomed girl. I didn't know if she could still be helped, but I had to track down whoever had created that vortex . . .

Just at that point I got a second jolt. But this time it was different. There was no cramp or pain, my throat just went dry and my gums went numb, the blood started pounding in my temples and my fingertips started itching.

This was it!

But the timing couldn't have been worse.

I got up – the train was already breaking as it pulled into a station. I walked past the girl and felt her eyes on me, following me. She was afraid. There was no way she could see the black vortex, but it was obviously making her feel anxious, making her pay close attention to the people around her.

Maybe that was why she was still alive.

Trying not to look in her direction, I put my hand into my pocket and fingered the amulet – a smooth cylinder carved out of cool onyx. I hesitated for a moment, trying to come up with some other plan.

No, there was no other way.

I squeezed the amulet tight in my hand, feeling a prickly sensation in my fingers as the stone began to warm up, giving out its accumulated energy. The sensation was no illusion, but you can't measure this heat with any thermometer. It felt as if I was squeezing a coal hot from a fire ... it was covered with cold ash, but still red hot at the centre.

When I'd drained the amulet completely, I glanced at the girl. The black twister was shuddering, leaning over slightly in my direction. This vortex was so powerful that it even possessed a rudimentary intelligence.

I struck.

If there'd been any Others in the carriage, or even anywhere in the train, they'd have seen a blinding flash that could pierce through metal or concrete with equal ease.

I'd never tried striking at a black vortex with such a complex structure before. And I'd never used an amulet with such a powerful charge.

The effect was totally unexpected. The feeble curses hanging over other people's heads were completely swept away. An elderly woman who'd been rubbing her forehead looked at her hand in amazement: her vicious migraine had suddenly disappeared. A young guy who'd been gazing dully out the window shuddered. His face relaxed and the look of hopeless misery disappeared from his eyes.

The black vortex above the girl was tossed back five metres, it even slipped halfway out of the carriage. But it maintained its structure and came zigzagging back through the air to its victim.

This was real power!

With real perseverance!

They say, though I've never actually seen it myself, that if a vortex is pushed even two or three metres away from its victim, it gets disoriented and attaches itself to the nearest person it can find. That's a pretty lousy thing to happen to anyone, but at least a curse meant for someone else has a much weaker effect, and the new victim has a good chance of escape.

But this vortex just came straight back, like a faithful dog running to its master in trouble.

The train was stopping. I threw one last glance at the vortex – it was back in place, hanging there above the girl's head, it had even started to spin faster . . . And there was nothing, absolutely nothing I could do about it. The target I'd been hunting all over Moscow for a week was somewhere close, right here in the station. My boss would have eaten me alive . . . and maybe not just in the figurative sense . . .

When the doors parted with a hiss, I gave the girl a final glance, hastily memorising her aura. There wasn't much chance of ever finding her again in this vast city. But even so, I would have to try.

Only not right now.

I jumped out of the carriage and looked around. It was true, I was a bit short of field work experience, the boss was quite right about that. But I didn't like the method he'd chosen for training me at all.

How in hell's name was I supposed to find the target?

Not one of the people I could see with my normal vision looked even slightly suspicious. There were plenty of them still jostling against each other here – it was the circle line, after all, Kursk station, there were passengers who'd just arrived on the main line, street traders making their way home, people in a hurry to change trains and head for the suburbs . . . But if I closed my eyes I could see a more intriguing picture. Pale auras, the way they usually are by evening, and in among them the bright scarlet blobs of fury, the strident orange glow of a couple obviously in a rush to get to bed, the washed-out brownish-grey stripes of the disintegrating auras of the drunks.

But there was no sign of the target. Apart from the dryness in my throat, the itching in my gums, the insane pounding of my heart. The faint taste of blood on my lips. A mounting sense of excitement.

The signs were all circumstantial, but at the same time they were too obvious to ignore.

Who was it? Who?

The train started moving behind me. The feeling that the target was near didn't get any weaker, so we still had to be close to each other. Then a train going in the opposite direction appeared. I felt the target tremble and start moving towards it.

Forward!

I crossed the platform, weaving between the new arrivals staring up at the indicator boards, then set off towards the back of the train – and my sense of the target began to get weaker. I ran towards the front of the train – there it was again . . . closer . . .

It was like that children's game, first I was 'cold', then I was 'warm'.

People were boarding the carriages. I ran along the train, feeling sticky saliva filling up my mouth, my teeth starting to ache, my fingers starting to cramp up. The music was roaring in my earphones.

In the shadow of the moon

She danced in the starlight,

Whispering a haunting tune

To the night. . .

How appropriate. The song was bang on.

But it was a bad omen.

I jumped in through the closing doors and froze, concentrating on what I could feel. Had I guessed right or wrong? I still couldn't get a visual fix on the target. . .

I'd guessed right.

The train hurtled on round the circle line. My instincts were raging, calling to me: 'Right here! Beside you!'

Maybe I'd even got the right carriage.

I gave my fellow passengers a surreptitious looking-over and dropped the idea. There was no one here worth taking any interest in.

I'd just have to wait, then . . .

Feel no sorrow, feel no pain,

Feel no hurt, there's nothing gained . . .

Only love will then remain,

She would say.

At Marx Prospect I sensed the target moving away from me. I jumped from the carriage and set off toward the other line. Right here, somewhere right beside me . . .