'What do you suppose that's meant to be?' Strangeways rubbed at the patch with his forefinger, then examined the tip. 'Plain black ink. Staines. Beauty spot. No, black spot.'

'Like an Accident Black Spot? How would we know which one? I remember seeing the signs when I was a kid. Do they still have them?'

'Shagged if I know. I'd like to help you out, but I don't think it's a telephone question. That's my specialist subject fucked. Check the envelope. There must be something else.'

Vince slid his hand back into the envelope. His fingers touched something gritty at the bottom. Carefully he turned it upside down and collected the residue. ' Crystals of some kind. Looks like salt.'

'Don't.' He pushed Vince's finger away from his tongue. 'Let me test it. If it's some kind of a drug I'll know.' He licked the tip of his finger and touched it to the sprinkle of white in the palm of his hand. Vince watched as he tasted the crystals and laughed. 'You're right, it's just plain rock salt. You know, sea salt. I don't get it. It's not a very good clue, is it? If that's the best they can come up with I'm most unimpressed.'

Vince looked up at the sky. From here, high above London 's bright centre, the clouds had broken and he could see an abyss of stars. The air was clearing now, but the temperature was dropping fast. A ghost-galleon of a cloud rolled lazily towards the moon, its hull illuminated by the city lights. The wind was rising.

'Sebastian's losing his touch,' he said finally, taking the page back and crackling it into his pocket. 'I know where this is. Too easy.'

'Look who's cocky all of a sudden.' Strangeways was crouching by his dog, feeding it a pepperoni stick. 'Can we play too, or don't you need us any more?'

That's what Sebastian's doing, thought Vince, sitting in the warm somewhere playing a game. He looked back at the dog. 'I guess you can come along. I may need someone who can get their head around the mindset of a juvenile.'

'Thanks a lot. So.' He rose and darted his head around conspiratorially. 'So where are we going, then?'

'To the South Seas. Treasure Island, of course,' Vince replied, swinging his leather bag onto his shoulder and setting off for the tube station once more.

'YOU'VE GOT to admire his gall if nothing else,' said Sebastian. 'Blatantly breaking the rules like that. The insolence is fucking incredible. Does he honestly think that we can't see him? That we don't know exactly where he is every damned minute of the night?' He rose, bringing his billiard cue back to an upright position. Somewhere to the rear of the gloomy room, Jessye Norman fulfilled the title role of Offenbach 's La Belle Hélène on a portable cassette player. Sebastian was very, very disappointed. He had expected a better show of gamesmanship from Vincent. The boy was simply not taking any of this seriously. How many people would they have to kill to prove the gravity of their intentions?

'Come along, Barwick, you glutinous little tick, it's your shot. Let's finish this game. I'm starving.'

'What are you going to do with him? Perhaps we should call the whole thing off.'

He pretended to consider the option, although nobody took Barwick's opinions seriously. 'I was rather wondering about that. I suppose I could put it to a vote.'

'The others have already gone into dinner. They'll agree with whatever you suggest. But something must be done. It's a clear breach of the rules. And he's already running late for the next challenge.'

'I know, I know,' said Sebastian irritably. He watched as Barwick spectacularly failed to pot the red. 'This game's going to go on all night if you don't start showing some finesse, Barwick.' He looked around for the end of his cigar. 'As I see it, we have two choices. One, we abandon the challenge in order to conduct the whole thing democratically, as Caton-James suggested from the start. Or two, we allow Reynolds to continue, but we punish him in order to acknowledge his breach of the rules. I vote for two. And you do as well, don't you?'

'Well, er, yes.' Barwick always did exactly as he was told. Sebastian set his cue back in the rack. 'Serious punishment is called for. Implement it, would you? Stir that unmetabolised sludge you call a body, go and talk to St John Warner. It'll mean interrupting him during his soup so he won't be very happy. And tell him not to leave connections, eh? Remember what happened last summer. You might try ringing Stevens direct.' Sebastian straightened his brocade waistcoat and checked his bow-tie in the tall gilt mirror that hung beside the table. 'I'll be down to dinner shortly. Now go about your task and don't be long about it.'

Barwick nodded anxiously. He was already punching out a number on his mobile phone as he hastened in the direction of the dining room.

It was only when he was alone that Sebastian was able to express his rage. He could not afford to let the others see him so vexed. Emotion of any kind was a sign of weakness, and they needed no encouragement to find fault with him.

The situation was controllable; it simply needed a firm hand. As in any game, penalties had to be exacted. It was important to deal with infringements swiftly and severely. Fucking little oik! No jumped-up, council-flat, white-trash wideboy was going to show him up before his peers and get away with it.

A glance in the mirror revealed that he was actually baring his teeth at the thought, growling rhythmically like some kind of inadequately caged panther.

'So,' he said aloud, 'you still think it's a game, do you? Let's see if you think that in an hour's time. Then, perhaps, you'll start doing what you're told.'

'Blind Pugh,' explained Vince. 'In Robert Louis Stevenson's Treasure Island Pugh holds out the piece of paper with the dreaded Black Spot on it.'

'The mark of disease,' said Strangeways. 'We could try a clap clinic. James Pringle House, I've been there a few times. I picked up a girl in their reception area once. We waited until we both had the all-clear, then went at it like goats.'

'There's supposed to be an ancient plague-site at Highbury Fields. They built windmills over it. It was said that the bread of London was ground on the bones of the city's dead. And plague victims were buried in the great pit at Cripplegate.'

'How come you know so much about it?'

'My specialist subject, this city,' Vince replied proudly. 'I've never had a chance to use the knowledge until now.'

'So where are we going?'

They were still waiting for a train on the empty platform at Golders Green station. The electronic board above them promised to deliver one in five minutes. London Transport minutes were longer than real-life minutes, and could be stretched infinitely.

'To Blackfriars.'

'Why there?'

'The Mermaid Theatre. Every year it stages Treasure Island at Christmas. Look.' A poster for the production had been pasted to the wall no more than ten metres from them. Previews were starting in a few days' time. 'Blind Pugh comes on stage waving the Black Spot about, frightening all the kids in the audience. The clincher was the sea salt, a bit of a giveaway, that. So, we just go there, retrieve the envelope -'

'Hold on, how long do you have to keep this up?'

'The challenges? There are supposed to be ten of them. This is the third.'

'And say you don't get completely cream-crackered from all this running about and manage to find all ten envelopes, then what's supposed to happen?'

'I win the right to go public with my story, the whole bit.'

'And you honestly think you'll be allowed to do that?'

The same thought had not left Vince's mind. 'These people pride themselves on being gentlemen,' he explained unconvincingly. 'It's what they hang onto most in life. Honour and duty. Victorian values. I think they'll stand by their word.'