But this sheet in his hand was proof of their existence, solid testimony. And even as he studied it, the paper began to dry and crumble in his fingers, splintering first in half, then quarters. A faintly bitter chemical smell arose as the craquelure deepened across the broken page, and the flakes of paper drifted to the floor, disintegrating further. They would not even allow him such meagre proof as this.

He looked at his watch. Twenty-past six. He checked inside the envelope. There was nothing else except the key. How could they be watching him? The telephone was less than a metre away from his right hand. Suppose he lifted the receiver and called the police? Could Sebastian's men somehow see into the flat? What could they possibly do, anyway? They were just trying to scare him, having a laugh at his expense.

If only he believed that. He had seen the silent fury on their faces when they had discovered him in the chamber. They had the means to get rid of him, and now he had given them the motive. Fuck, fuck, fuck, what to do. It was coming up for six-thirty. If he accepted the challenge, he only had half-an-hour in which to find a use for the key.

They had to be able to see in somehow. Very slowly, he moved in front of the window and tried to look into the rooms on the other side of the street. The sudden racket of the telephone took a year off his life. He allowed it to ring three times before lifting the receiver.

'I hope you haven't forgotten about tonight,' said Pam.

'What?' Relief flooded through him.

'We're having dinner tonight, remember? You've blown me out twice recently, and I'm not standing for it a third time. Amazing as it may sound, I do have a scrap of pride left, you know.' Her tone was playful. The last thing he needed right now.

'Listen, Pam, I've got some kind of – thing – going on here and -'

'I have to win you away from that computer somehow, so I'm offering to pay for the meal. You're allowed dessert and everything.'

'I don't think I can -'

'No "no" for an answer this time, sonny boy, you promised, remember?'

'You're right,' he admitted, 'I promised.'

'So I'll see you at eight-thirty, as we arranged. Resistance is futile. I'm looking forward to it already. A tout à l'heure, saucepot.' She rang off.

He picked up the key once more and tried to think. The telephone rang again. This time he answered before the end of the first ring.

'I hope you slept well last night.' The voice was amused, male, almost playful. 'You received your instructions, I hope. This night will require all the intellectual and physical energy at your command if you are to survive it. You really should have started by now. You're going to miss your deadline. You've only until seven o'clock to use the key, or you're out of the game.'

'I'm not playing your stupid games, Sebastian, you can go fuck yourself -'

'There's that gutter language again. So limiting, when there are so many beautiful English words to choose from. In case you had trouble with the title of the challenge, by the way, Deca -'

'- diurnal means in a cycle of ten, ten challenges, yeah, I figured that part, I'm common but I'm not completely stupid.'

'You're not allowed to take anything with you that you would not normally be carrying on the street. I think we forgot to mention that.'

'I'm not doing this, Sebastian, I already told you.'

'If you don't you will be killed, and others may be hurt too. We are deadly serious about this, Vincent. You're not the first to stand accused. But you could be the first to win. Where's your sense of gamesmanship?'

'And if I win, what does my victory entitle me to?'

'It grants you the title of "Grand Master Of The City". You get a badge, a hat and everything. More importantly, you win the right to publish. We'll be in touch again. Right now it's six-thirty-two precisely. You'd better get going. There's only a short time left for you to reach the base-point of your first challenge. The time limit for each section of the night will be given to you in due course. Now, if you're not out of that gruesome little flat in the next few minutes, we will claim our forfeit, invade your life and bury your pathetically miserable soul in pieces so far apart that no two people in the same time-zone will be able to find it.'

The line went dead.

It took him exactly two minutes fifty-five seconds to load his leather duffel bag and hit the street running.

VINCE TURNED the tiny steel key over in the palm of his hand, tipping it to the light. There was something engraved on either side. On one, the number 12. On the other, a longer series of numerals. He tilted it back and forth until he could read the inscription. 18371901. Some kind of serial number, perhaps. There were no other markings.

Now what?

He was standing in the street, outside the Hallmark card shop three doors along from his flat. The hazy winter night was sharpening with sporadic gusts of rain, finer than sea spray. He found it hard to believe that they were really watching him. That evening in the Holborn chamber he had only seen a few of their faces; he would remember Barwick's moley features, but none of the others. And they were only the members of the inner circle. What was it Dr Masters had said about there being as many as fifty in the League? It was clear that he had to go along with this lunacy, at least until he figured out if they were just trying to scare him, or whether they really meant business.

He tried to recall his arrangement with Pam tonight. They were going to eat, then meet up with Louie, who was heading for a gig at the Jazz Café with some people from college. If he didn't show up she'd be annoyed with him, and might think it odd. Failure to appear was pretty normal behaviour within their group but Vince was known for reliability. He should have told her about the letter. Now it was too late. The rules forbade him from calling her back. He could feel the panic of indecision setting in.

Concentrate on the problem instead, he decided. Look at the key.

He studied the numbers again.

12 and 18371901.

They meant nothing to him. Serial numbers for a standard key, the key to anything from a bicycle lock to a petty-cash box. Big deal.

If he was going to get through this, he knew he would have to start thinking like Sebastian.

'Hey Vince, you okay, man?'

There was a crash behind him as Mr Javneesh pulled down the shutter of the card shop window. He had installed a new display of birthday cards that celebrated the recipient's year of birth. Each card had a montage of that year's events depicted on its cover, and featured the date in large black letters. 1953. 1965. 1972. He had been meaning to buy one for Pam.

'You should get inside, man. Looks like rain.' Mr Javneesh zipped up his jacket and headed off towards his car. Vince looked back at the numbers on the key. 18371901.

Could they be dates? 1837 – 1901?

Sixty-odd years. He looked back at the cards. Sixty glorious years. Queen Victoria 's reign. Victoria. His fingers gripped the key. A locker key. The left-luggage lockers at Victoria station.

He was on his way.

The litter-filled ticket hall at Tufnell Park tube station was crowded with loitering drunks and wild-haired kids. As he punched coins into the ticket machine he wondered if members of the League were watching him.

'Oi, you got any spare change?' A sixteen-year-old white boy with dreadlocked yellow hair and a blue nylon sleeping bag wrapped around his shoulders was tapping him on the back. He stared at the boy in alarm. What would happen if he replied? Would they hurt the boy? He bolted for the escalator and the safety of the underground platform, unable to shake the feeling of being monitored. There were closed circuit security cameras mounted at either end of the platform. Who was studying their screens?