After a revolting supper of meat balls and Lambrusco, served up by a harassed-looking Sam, Louis and his fellows packed up their briefcases, pumped my hand and nodded their heads meaningfully, before climbing into their cars and setting off back down the yellow brick road. I didn’t wave.

Instead, I told the Carls that I was going for a walk and went through to the garden at the back of the house, where a lawn ran down to the river and a view of the most beautiful reach in the whole length of theThames.

It was a warm night, and on the opposite bank young couples and elderly dog-walkers were still promenading. A few cabin-cruisers had moored nearby, water patting gently against their hulls, and the lights at their windows glowed a soft and welcoming yellow. People were laughing, and I could smell their tinned soup.

I was in deep shit.

Barnes arrived just aftermidnight, and he was a very different sight from our first meeting. The Brooks Brothers stuff had gone, and he now looked like he was ready to head into the Nicaraguan jungle at the drop of a bomb. Khaki trousers, dark-green twill shirt, Red Wing boots. A military-looking watch with canvas strap had taken the place of the dress Rolex. I had the feeling that for two pins he’d have been in front of a mirror, slapping camouflage paint on to his face. The lines were deeper than ever.

He dismissed the Carls and the two of us settled ourselves in the drawing-room, where he unpacked a half-bottle of Jack Daniels, a carton of Marlboro and a camouflage-painted Zippo lighter.

‘How’s Sarah?’ I said.

It felt like a silly question, but it had to be asked. After all, she was the reason I was doing all this - and if it turned out that she’d stepped under a bus that morning, or died of malaria, I was definitely off the case. Not that Barnes would tell me if she had, but I might get something from his facewhenhe answered.

‘Fine,’he said. ‘She’s just fine.’ He poured bourbon into two glasses, and skidded one of them across the parquet floor to me.

‘I want to speak to her,’ I said. He didn’t flinch. ‘I need to know she’s all right. Still alive and still all right.’

‘I’m telling you she’s fine.’ He took a suck at his glass.

‘I know you’re telling me that,’ I said. ‘But you’re a psychopath, whose word isn’t worth a flake of sick.’

‘I don’t like you much either, Thomas.’

We were sitting opposite each other now, drinking whisky and smoking cigarettes, but the atmosphere fell short of the ideal agent-handler relationship, and was falling shorter by the second.

‘You know what your problem is?’ said Barnes, after a while.

‘Yes, I know perfectly well what my problem is. It buys its clothes from an L.L. Bean catalogue, and is sitting opposite me right now.’

He pretended he hadn’t heard. Maybe he hadn’t.

‘Your problem, Thomas, is that you’re British.’ He started rotating his head in odd movements. Every now and then a bone cracked in his neck, which seemed to give him pleasure. ‘The things that are wrong with you, are wrong with this whole godforsaken pisspot of an island.’

‘Wait a minute,’ I said. ‘Wait a full, well-rounded minute. This can’t be right. This can’t be a fucking American, telling me what’s wrong with this country.’

‘Got no balls, Thomas. You ain’t got them. This country ain’t got them. Maybe you had them once, and you lost them. I don’t know, and I don’t care so much.’

‘Now Rusty, be careful,’ I said. ‘I ought to warn you that over here, people take the word "balls" to mean courage. We don’t understand the American meaning, of having a big mouth and getting an erection every time you say "Delta" and "strike" and "kick ass". Important cultural difference there. And by cultural difference,’ I added, because the blood was running a bit hot I must admit, ‘we don’t mean a divergence of values. We mean fuck you up the arse with a wire brush.’

He laughed at that. Which was not the reaction I’d been hoping for. Quite a large part of me had hoped that he’d try and hit me, so that I’d be able to punch him in the throat and ride off into the night with an easy mind.

‘Well, Thomas,’ he said, ‘I hope we’ve cleared some air there. Hope you feel better now.’

‘Much better, thank you,’ I said. ‘Me too.’

He got up to refill my glass, and then dropped the cigarettes and lighter in my lap.

‘Thomas, I’ll be straight. You can’t see, or speak to, Sarah Woolf right now. Just ain’t possible. But at the same time, I won’t expect you to lift a finger for me until you have seen her. How’s that? Sound fair enough to you?’

I sipped at the whisky and eased a cigarette from the packet.

‘You haven’t got her, have you?’

He laughed again. I was going to have to put a stop to this somehow.

‘I never said we did, Thomas. What did you think, that we had her chained to a bedpost somewhere? Come on, give us a little credit, will you? We do this for a living, you know. We’re not right off the boat here.’ He dropped back into his chair and resumed his neck-stretching, and I wished I could have helped. ‘Sarah is where we can reach her if we need to. Right now, seeing as how you’re being such a nice little English boy, we don’t need to. Okay?’

‘No, not okay.’ I stubbed out the cigarette and got to my feet. It didn’t seem to bother Barnes. ‘I see her, make sure she’s all right, or I don’t do this. Not only don’t I do this, I might even kill you just to prove exactly how much I’m not going do it. Okay?’

I started slowly to move towards him. I thought he might cry out to the Carls, but that didn’t worry me. If it came to it, I only needed a few seconds - whereas the Carls would take about an hour to get those ridiculous bodies kick-started into action. Then I realised why he was so relaxed.

He’d dropped his hand into the briefcase at his side, and there was a glint of grey metal as the hand emerged. It was a big gun, and he held it loosely over his crotch, aimed at my midriff, range about eight feet.

‘Well Jiminy Cricket,’ I said. ‘You’re about ‘to get an erection, Mr Barnes. Isn’t that a Colt Delta Elite you’ve got there in your lap?’

He didn’t answer this time. Just looked.

‘Ten millimetre,’ I said. ‘A gun for people who’ve either got a small penis or little faith in their ability to hit the middle of the target.’ I was wondering how to cover those eight feet without him hitting me with a decent body shot. It wasn’t going to be easy, but it was possible. Provided one had balls. Before and after the event.

He must have sensed what I was thinking, because he cocked the hammer. Very slowly. It did make a satisfying click, I must admit.