'I know you, Sebastian. You like a bit of strident marching music. You like Offenbach, Gilbert and Sullivan. And just like Gilbert, you love a good paradox. How could you have resisted this?'

'You're right, I couldn't. I decided to give the leadership contest some bite. It was a chance to further the original purpose of the League. An opportunity to bring the fire of enlightenment to the nation.'

'And a chance to get back at your father.'

'Don't be impertinent. You know nothing about Nicholas.' He pulled a hand from his pocket and drained his brandy glass. 'My father was always aware of my ambitions, right from my fourth-form years at public school. But he didn't believe that I could ever develop leadership qualities. My mother was a "woman's woman". Politics bored her. I was her only issue. Nicholas felt I was too much of a "loose cannon". A favourite expression of his. Felt I lacked discipline. I was allowed a small amount of youthful freedom, but beyond a certain point the parental noose tightened. Do sit down, you're making me nervous.'

Vince remained standing. He doubted his ability to rise again if he sat now.

'I headed off to university. During one autumn break, my father set me a test. Turned out that the old man was a bit of a game-player himself. He threw me a spectacular party, provided me with plenty of temptation, and sat back to watch me throw away my future. He knew my weaknesses, you see. He knew that I would let him down.'

'What kind of father would do that?' asked Vince.

'A pity you never got to meet him. You'd understand a lot more about me.'

'I understand a lot more than you think. I know you want to be me.'

'Oh?' Sebastian raised an eyebrow. 'What is it about you that I covet so much?'

'My freedom. Something you've not had since the night your girlfriend drowned.'

'I wondered if you'd find out about that.' Searching for something else to drink, he located a fifth of scotch beneath the chair. He unscrewed the cap and drank from the bottle. The action was uncharacteristic and sat awkwardly on him, like a badly-cut jacket. 'When I discovered Melanie unconscious on the pier that evening, I panicked. She drank, enjoyed her party drugs, was always pushing the limit, just like the rest of us. Her skin was almost blue. She was so cold to the touch. There seemed to be no pulse. You must understand. I thought she was dead. I thought I'd be blamed. I had already assumed that father wouldn't help me out if there was any kind of trouble. I saw myself losing everything I had worked for.

'I simply nudged her body with my foot and she rolled from the pier into the water. There was hardly even a splash. Then I walked back to the dance-tent and poured myself a drink. Nobody saw what had happened. Her body wasn't discovered for ages. When it was, my father surprised me by offering to help. The old man made sure that the coroner's verdict went in my favour, and that I would be forever in his debt. He understands the power of emotional blackmail. He didn't want to make me hate him. Quite the opposite. He wanted to make me hate myself. He proved how much I needed him. Every time I looked at his smug face I could hear him saying "I told you so".'

'So you searched for a way to get back at him.'

'The League members wanted a test of my abilities. My father wanted the free-migration vote to be passed. And I wanted revenge against you. It was my chance to tie the whole thing up in one neat package, and the beauty of it was, it would only take a single night to sort out the troubling strands of my life – one night, ten hours – and all my problems would be solved. Well, I suppose now they are solved.'

'What do you mean?'

'My agreement with the other League members was that I would admit defeat if you managed to beat me. I do not acknowledge your victory. But I have a feeling that the members will. In which case, I must formally ask if you would be prepared to accept unconditional membership into the League of Prometheus. I am also duty-bound to inform you that if you accept the offer, I must fulfil the final part of my contract with the League.'

'Which is?'

Sebastian looked straight ahead. His pupils had flattened into distant green disks. 'Obviously, I'm required to take my own life.'

'I don't understand,' said Vince. 'You set up this night of challenges yourself. You planned it.'

'That is correct.'

'Then why on earth didn't you make it impossible for me to win? Why did you set me tasks that you knew I would have to solve in order to fulfil your other purpose? If you wanted to get back at your father, why not do it another way? You could only beat him by allowing me to win. You deliberately created a situation in which your main purposes cancelled each other out. Why would you do such a thing?'

Sebastian raised his dead green eyes. He looked older in the growing light. 'As you yourself pointed out, I am very fond of paradoxes,' he said, smiling coldly.

'So you've lost and won.'

'That's the best result I could ever have hoped for. The resolution of this night is now in your hands.'

From the street below came the whine of a milk float making its deliveries. The rain was finally easing, but the sky remained grimly dark. Sebastian rose unsteadily and unstuck half a bottle of claret from the sideboard. The atmosphere in the room was fetid and heavy.

'Well, what's it to be, young Vincent?' he asked, tipping the bottle over his glass and slopping wine on the floor. 'Do you accept the offer and take over as part of the League's new "grass roots" order? They'll guarantee you won't be implicated in the night's events. It's simply a matter of a few phone calls. Could you be seduced by the thought of such power and spend the rest of your days with my death on your conscience?'

He set down his wineglass and dug inside his jacket. 'It's a service revolver,' he said, brandishing the dull grey pistol. 'Holds an important ceremonial role in the League's traditions. It's been used many times before, for many different reasons.' Removing the safety catch, he raised it to his throat and tilted his face to the ceiling. 'God, you spend years trying to change the world, only to discover the final hellish paradox.'

'Which is?' asked Vince, watching him and waiting for a chance to snatch the gun away.

'That the good intentions die with you, and the evil ones live on.' His finger tightened on the trigger as he slowly tipped his chair back. 'You'd better get out of here before the sound of the shot brings the others running.'

'No way,' said Vince, shifting forward. 'I want to make sure you pull the fucking trigger.'

Sebastian was so surprised he nearly shot himself.

'Come on, then, do it. You don't get off the hook by chucking me a bit of paraphrased Shakespeare and hoping I'll buy it. Let's see you take the noble way out, do the decent thing. Open the tent flap, look over your shoulder and tell me you might be gone for some time.'

Sebastian held the pose, but his eyes flicked uncertainly back at Vince.

'Go on, join an illustrious gallery of honourable suicides. How old was Brutus when he killed himself?'

Sebastian remained motionless for a few seconds more, then started to waver. 'Jesus.' He lowered the revolver. 'I think it's quits, don't you? You're not about to join our ranks, and somehow I don't think we'll ever be able to join yours. The poor old Prometheans are like this city; we're carrying too much baggage to ever start entirely afresh. We'll still be here next month, next year; a little older and shabbier, but still here. And no doubt it will be the task of someone like you to cancel out each forward move we make.'

Vince gave a rueful smile. 'Then the game would continue for ever.'

'Of course.' Sebastian laughed. 'How could it ever end?'

'But it has ended,' said Vince, seating himself at the other end of the table. 'You see, there's one final paradox you haven't considered.'