'I don't know. I'm feeling it already with the painkillers.'

He gave me a sly smile. 'Come on. Drown the sorrows. You can always sleep it off later. Remember, you've done your bit.'

Like a lot of City boys, Dom had always drunk a lot. It was an easy way to handle the pressure and the long hours. I'd never caned it to quite the same extent, but I figured another bottle probably wouldn't do a huge amount of harm. There was nothing else I could do to find Jenny, so I might as well forget about it for a while. 'Go on then,' I said. 'In for a penny and all that.'

He looked pleased – after all, no one likes to drink alone – but as he left the room I realized that something was bugging me, although in the fog of the booze it was difficult to identify what it was.

Then I remembered.

I hadn't told Dom about the GPS transmitter in my mobile. I went back through the conversation we'd had, trying to work out if I was mistaken.

Then something else hit me, its ramifications so immense and terrifying that I suddenly sat bolt upright on the sofa.

Maxwell didn't have mobile reception at his place.

He used to say he was happier without it because only a handful of people had his landline number, which meant only people he wanted to speak to could get hold of him. It meant that when I interviewed him for the book, I never got interrupted.

So the kidnappers couldn't have used the GPS to find me there. Which could only mean one thing: they'd had inside information from somewhere.

And as I turned towards the door, I knew immediately where it had come from.

The smile on Dom's face died the moment he came into the room and saw my expression. I think in that moment he knew that I'd found him out.

'What is it, Rob?' he asked with a casualness that seemed forced as he put the bottle of Sauvignon Blanc down on the table.

'Where's Jenny, Dom?' I demanded.

'What are you talking about? How should I know?'

I told him about the lack of a mobile reception at Maxwell's place.

'What the hell's that got to do with me?'

'You knew where Maxwell lived, didn't you?'

'Well, yeah, but so did quite a lot of other people.'

'But none of them were intimately acquainted with Jenny, were they?'

Part of me couldn't believe I was saying what I was saying. After all, Dom was my friend of more than twenty years, a normal guy who'd lived a normal life and who'd never been in trouble before. Yet when I'd spoken to him on the phone in Dubai the other day, something hadn't rung true. It was the way he'd denied that he'd talked to Jenny for months, even though she'd told me he'd been calling her, trying to get back together. Because why on earth would she have made something like that up?

'You were lying when you said you hadn't spoken to Jenny for months, weren't you? So tell me,' I said, raising my voice now, 'where the hell is she?'

'Christ, Rob, don't be so fucking stupid. Why the hell would I ever get involved in a kidnapping? I'm a businessman, not a criminal. You're delirious, mate. You need some rest.'

He tried staring me out, wearing an expression of righteous indignation and surprise that I'd seen him use plenty of times, usually when he was trying to convince someone he was telling the truth. It usually worked, too, and was doubtless one of the reasons he'd been so successful in business. Back in the old days it had always convinced our teachers he was telling the truth. But I knew him too well. Most of the time he did it when he was lying.

As if to confirm my suspicions, the skin beneath his right eye began to twitch, a long-standing habit that invariably occurred when he was under stress.

I felt the rage building in me. 'You bastard! Where is she? Where's Jenny?'

'What the fuck are you talking about?' he shouted, his voice filling the room. 'You're fucking delirious, Rob, so don't say stuff you don't mean, all right? Why don't you just go for a lie down or something? OK?'

'Where is she? Is she still alive?'

'Shut the fuck up!' he hissed, the guilt coming off him in waves.

'I'm going to call the police, Dom. Right now. I've got the number of one of the senior guys on my phone. Maybe you can convince him you don't know what's happened to Jenny, because you know what? You're not convincing me.'

I stood up and pulled the phone from my pocket with my good hand, still finding it almost impossible to believe that this was happening. Of all the shocks I'd had recently, this was undoubtedly the biggest of all. Which was why, I suppose, it had taken me so long to work it out.

'Put the phone down, Rob,' said Dom with an icy calm. 'Now.'

'No.'

The punch came out of nowhere, connecting perfectly with my jaw and sending me crashing back on to the sofa. The phone flew out of my hand, thudding on to the carpet somewhere out of sight.

Before I could react, Dom grabbed a cushion from one of the sofas and sprang across the coffee table, his face contorted with an angry panic I'd never seen there before. He landed on top of me, one leg digging into my broken arm, and I cried out in pain, trying to avoid the blows raining down on me. Then suddenly the cushion was being pushed into my face and I could no longer see anything. I struggled under him, but he was an ex-rugby player, and even though he'd lost weight he was still a big guy, and in my condition it was always going to be an unequal battle.

I heard him grunt with exertion as he forced the pillow down hard and I felt the panic surge in me as my breath became trapped in my throat. I grabbed his thigh with my good hand, squeezing it as hard as I could. I wanted to beg him for mercy, to tell him that if only he let me go I wouldn't say a word. But only muffled gasps came out as I fought for air.

Without warning, the cushion was pulled away. Dom was staring down at me, tears in his eyes. 'You fucking prick!' he shouted, bringing back his fist. 'Why did you have to get involved? Why couldn't you have just kept out of it and got your own fucking girlfriend? Then none of this would have happened!'

I started to say something but he punched me again, full in the face, although this time there was less power in the blow. I could tell then that he was incapable of killing me. I could hardly move, and my arm was in so much agony I thought it might have been broken again. Even so, I felt hopeful, because it seemed that Dom still possessed some kind of conscience.

He stood up, breathing heavily, clenching and unclenching his fists. Thinking.

Spitting blood from my mouth, I spoke through gritted teeth. 'If you tell me where she is, Dom, I'll call the police anonymously and give them the location. I won't mention your name, I promise.'

'I don't fucking know, all right!' he shouted, pacing the room. 'I haven't got a clue where she is!'

'So what's going on, Dom? Tell me. Please. I'm your mate.'

He gave a sort of groan. 'You were, Rob. But not any more.'

'I can help you. Honestly.'

'No, you can't. You most definitely fucking can't. The only people who can help me are not going to want you shooting your mouth off.'

'I'm going to leave now,' I said, getting unsteadily to my feet, ignoring the way the room was spinning. 'I won't say a word. I promise.' But my plea sounded hollow, and we both knew it.

Dom shook his head firmly. 'I'm sorry, mate, but I can't allow you to do that.'

Knowing I had no choice, I started towards the door, giving him the kind of anguished, vulnerable look I hoped would make him feel sorry enough for me that he wouldn't intervene.

He blocked my path, and I saw that his expression was hard and determined.

I went for the bottle of Sauvignon Blanc on the coffee table, but the booze and pills had made me way too slow, and he knocked me out of the way and grabbed it himself.