At 1.05 that afternoon, I was sitting on a bench in Regent's Park smoking yet another cigarette and waiting for my rendezvous. The rain had long since cleared and it was even threatening to be quite a nice day. I'd already attended the briefing session back at the station where Knox had worked hard to instil some enthusiasm and grit into the inquiry, not an easy task as no-one felt there was much hope of intercepting the perpetrator quickly. I'd now got Malik on to the task of identifying her, which, if she was a Tom, wouldn't take too long.

I liked Malik. He wasn't a bad copper and he was efficient. If you asked him to do something, he did it properly, which doesn't seem to be a common trait with a lot of people these days. And he wasn't idealistic either, even though he'd only been in the Force for five years and was university educated, which is usually a pretty dire combination. So many of the fast-track graduates who go shooting up through the ranks have all these big ideas about trying to understand the psychology and economics of crime. They want to find out what motivates and drives criminals rather than simply doing what they're paid to do, which is catch them.

I looked at my watch again, which is something I do constantly when I'm early for a meeting or the other person's late. In this case, the other person was late, but then Raymond was never the most punctual of people. I was hungry. Apart from the toast I'd forced down myself earlier that morning, I hadn't eaten in close to twenty-four hours and my stomach was beginning to make strange growling noises. I was, I decided, going to have to improve my diet and start eating more regularly. One of the DCs had told me that sushi was very good for you. The Japanese eat it all the time and, according to him, they have the lowest incidence of lung cancer in the industrialized world, even though they're the heaviest smokers. Raw fish, though. It was a high price to pay for a life of rude health.

'Care to join me for a walk, Dennis?' said Raymond, interrupting my thoughts. 'Or would you prefer to continue your meditation?'

There he was, bright as a bell, a wide smile on his big round face, as if the whole world were his playground and all was fair within it. That was Raymond Keen for you. He was one of those big, bouncy guys who simply oozed joie de vivre. Even his haircut, a magnificent silver bouffant of the kind so beloved of middle-aged men who want to put one over on their balding contemporaries, and which sat on the top of his head like a curled- up Cheshire cat, seemed designed to tell the world what a jolly character he was. Which was a little odd when you considered that one of his more active and lucrative sidelines was running a funeral parlour. But Raymond, as became clear when you got to know him, was a man with a deeply ironic sense of humour.

'I'll join you, I think,' I told him.

I got up and we started to walk across the grass in the direction of the boating lake. Some kids who should have been in school were playing football and a few mothers were out strolling with pushchairs, but other than that the park was quiet.

I didn't beat about the bush. 'What the fuck happened, Raymond? You told me I was shooting drug dealers.'

Raymond attempted a rueful smile but he didn't look overly guilty. 'Give me a break, Dennis. I could hardly have told you the real targets, could I? You wouldn't have shot them.'

'I know I wouldn't have shot them! That's the point. You got me involved in something that's against everything I stand for.'

Raymond stopped and looked at me, a smile playing on his lips. Angry or not, it was obvious he knew there was nothing I could do about the situation. He had me pinned, and he knew I knew it.

'No, Dennis. That's where you're wrong. You got yourself involved. Admittedly, I embellished the truth a little bit-'

'You mean you lied.'

'But I needed them out of the way, and knowing – and all credit to you for this, Dennis – knowing your moral standpoint on this sort of thing, I thought I'd withhold some of the details. But I don't want you to lose sleep over it. These blokes were pondscum. They were blackmailing some associates of mine and the associates wanted them out of the way.' He sighed meaningfully. 'They were corrupt men, Dennis.'

'And that's meant to make me feel better, is it?'

'If it's any consolation to you, it makes me feel bad as well. I don't like the idea of men dying. Human life is a very precious thing, not to be taken away lightly. If there was any other way, any other way at all, you can claim a bet that I would have tried it.'

The phrase 'claim a bet' was one of Raymond's favourites, even though it meant absolutely nothing, and I'd never in my life heard a single other person utter it. Hearing it now annoyed me.

'Raymond, you have fucked me up. Do you have any idea the sort of pressure the murder of customs officers is going to generate? It's not like shooting three dealers who no-one's going to miss. These were family men who died doing the job they loved.'

'They were blackmailers who died because they were trying to blackmail the wrong sort of people. That's what they were.'

'But that's not what the media are going to say, is it? To them, these guys are the thin blue line, brutally murdered in the line of duty. They're going to be clamouring for a result on this. And you can claim a fucking bet on that.'

'Don't be facetious, Dennis.'

'I'm being serious. Deadly serious. The pressure to get a result on this one is going to be massive.'

'But they're not going to get a result, are they? We've done everything needed to cover our tracks. It was a well-planned operation. All credit to you for that, Dennis. It was a professional job.'

He started to walk again, and I followed. To him, the conversation was effectively over. He'd said his piece, tried to smooth the ruffled feathers of his part-time employee, and now it was time to move on.

I then did a stupid thing, a very stupid thing, that was to cause me and plenty of other people a lot of grief. I told him I'd been seen.

That stopped him dead. Which, of course, I knew it would.

'What do you mean?' There was an edge to his voice now and I wasn't sure if it was anger or nervousness. Probably both. Immediately I regretted opening my mouth. I'd just wanted to punch a hole in the smug air of confidence he was exuding, and it looked like I'd been only too successful.

'I mean, I was seen. One of the staff, a kitchen girl or something.'

'Did she get a good look?'

'No. It was dark and raining, and she was a fair way away.'

'How far?'

'Fifteen, maybe twenty yards. And I had my head down. I doubt if she could give much of a description.'

'Good.' He seemed mollified. 'Why didn't they say anything about that on the news?'

'On something like this, where there's evidence that it was a planned killing, they won't want to risk putting the witness in any danger. Also, they'll still be questioning her.'

'How come you didn't shoot her?'

'Would you have wanted me to?'

'Well, it mightn't have been a bad idea.'

'What? Four killings? Come on, Raymond, this is England, not Cambodia.'

'Well, if you didn't think she saw anything, then I suppose there'd have been no point.'

'I don't think she saw anything.'

'Maybe not, then. There's no point killing anyone unnecessarily.'

'Especially when human life's such a precious thing.'

Raymond glared at me. He wasn't the sort of man who liked having the piss taken out of him. 'I don't really think you're in a position to get on your high horse, Dennis, do you?'

'So what were these customs men doing, Raymond, that was so bad they had to die?'

'As I said, they were blackmailing some associates of mine. Associates who are very important to the smooth running of my business.'