Tina stiffened. She thought of the photo of Gentleman's granddaughter on the mantelpiece.

'He was a pain in the arse,' continued the man with the gun, enjoying her reaction, leaning forward now so his mouth was right next to her ear, stroking the gun against her belly. 'I'd like to have finished him off more slowly – it's always more… satisfying that way – but I didn't have the time.'

He ran his lips across her earlobe, licking and nibbling it. 'Give me your phone,' he whispered gently. 'And don't hesitate or I'll kill you.'

Tina's skin was crawling but she refused to allow herself to flinch or pull away. Prising one hand from the wheel, she took it out of her pocket and handed it over.

As he flipped open the cover and began scrolling through the menu, Tina came to a halt behind stationary traffic at the next junction, and once again she thought about escape. It was a huge risk as this bastard definitely wasn't bluffing. But it was an even bigger one staying put, because she was pretty damn sure he wasn't going to let her live.

'Ah, so you weren't talking to your colleagues when I arrived. You were talking to another of our mutual friends, Mr Fallon. Now, he really is a pain in the arse. Are you sure you're a police officer? You wouldn't be joshing me now, would you?' His tongue flicked out like a lizard's, wetting his lips.

Then, without warning, he lunged forward, forcing the gun between her legs so that the end of the silencer was pushed hard against her groin. 'What's going on?' he demanded, his eyes boring into the side of her face. 'Tell me or I'll shoot you right here, right now.'

'I'm moonlighting,' Tina answered with an unavoidable flinch, staring straight ahead, only vaguely aware of the world outside. 'Doing work for Fallon.'

'Interesting. He really is very persistent.'

As the traffic began to move again, he switched the phone off, snapped off the cover with his teeth, pulled out the SIM card and pocketed it, then opened the window and threw out the pieces.

Tina cursed inwardly. This guy knew what he was doing, getting rid of the one item that could be used to trace her.

He picked up the Nikon. 'Now, these photos you took. Did you send them to Mr Fallon?'

'No,' she said firmly, hoping fervently that he hadn't been watching her car when she sent the photos on the laptop. She was just trying to stay alive now, hoping that if he didn't think she'd done that much to ID him he might let her go. It was a long shot, but when you've got a gun thrust between your legs, you tend to cling to long shots.

The man with the gun deleted the photos from the Nikon with his free hand and casually tossed it out of the window.

A bead of sweat ran down Tina's eyelid and into her eye. She blinked it away angrily. 'That camera cost me five hundred pounds,' she said coldly.

'If you hadn't been snooping around in other people's business, you wouldn't have lost it.'

She wiped her forehead, feeling a desperate urge for a cigarette. 'Do you mind if I smoke?'

'You've a gun pressed into your cunt and you're thinking about your next cigarette?' He chuckled again. 'You've got spirit, my love. I like that. Go on then.'

Tina reached down and pulled the pack and the lighter from where they were nestled in the cup holder. 'Do you want one?'

'No thanks. I prefer more enjoyable vices.'

He slipped the gun out from between her legs and rubbed it gently up and down her thighs, never taking his eyes off her.

Ignoring his gaze, Tina lit a cigarette and took a long drag, knowing that it was essential she keep talking to him. It was always more difficult to kill someone when you'd established a connection with them, although this guy sounded like he might well be the exception to the rule.

'Have you noticed something?' she asked him.

'What?' He sounded interested.

'I haven't looked at you once. I haven't seen your face.'

'You took those photos of me, didn't you?'

'From a distance, and with you wearing sunglasses and a cap. I can't describe you. Also, I've got no incentive to go to the police. I got Fallon to call Gentleman to try to panic him, so if you've killed him, then that's my fault. In other words, I'm going to keep quiet. So, rather than kill me and open up a whole world of shit, you might as well let me go. I'll get out of the car and I won't say another word to anyone. I promise.'

Out of the corner of her eye she saw his smile widen a little.

'Thanks for the advice,' he said, 'but it's OK.' He leaned forward again, running his nose softly up her neck. Sniffing. 'I'm quite enjoying the company.'

'What are you going to do to me?' she asked, trying hard to keep her voice even, more frightened than she'd been in years. Perhaps ever.

'Why, I'd have thought that was obvious,' he said quietly. Then he grabbed her by the chin, jerking her face round so she was looking directly into his pale face, even though they were travelling at close to thirty miles an hour. 'I'm going to kill you.'

It had just turned four o'clock when I finally found an internet café on a side street near Bloomsbury in the heart of the West End, and signed into my email account. The day was sunny, the streets were crowded, and I was hot and bothered, having been trooping round for much of the afternoon buying clothes and provisions and then looking for somewhere to check my mail, all the time waiting for news about what Tina was up to, because it was clear she was up to something.

I clicked open her email, saw the message, and downloaded the photos.

The first one stopped me dead. It was him. The strange-looking Irish kidnapper. I could only assume Tina had taken this photo outside John Gentleman's place. Seeing his face now made me go cold, bringing back black, terrible memories that I knew were going to stay with me for the rest of my days. I scrolled through more of the photos, finding it difficult to believe that this man had abducted Jenny and murdered Ramon in cold blood. He looked so much more ordinary in a cap and sunglasses.

I wear a four-gigabyte memory stick round my neck which contains my most up-to-date drafts of Conspiracy as well as my book on Maxwell, and I copied all the photos on to it. I'm not the kind of person to rely too heavily on technology, though, so before I deleted them on the PC I printed them off in colour on one of the café's printers, paid the blank-eyed man at the desk, and headed out.

Now that the Irishman had finally come out into the open, I was itching for an update from Tina. In our last conversation she'd said she'd call in an hour, but that was an hour and twenty minutes ago, so I figured I could get away with hassling her.

Her phone was switched off. I waited five minutes, then tried again. Same message. I remembered only too well what this man was capable of – how he'd managed to conceal himself in my flat, listening to Ramon and I talking before striking silently and coldly in the space of seconds. If Tina had been taking photos of him, she'd have had to get close. Maybe too close.

I walked the streets of the West End for a while, trying her number, always in vain, waiting for a call that I had an ominous feeling was not going to come.

And it didn't.

My car was parked near Belsize Park Tube station and I took the Northern Line to get it. By the time I arrived, I had a plan. It was a fairly basic one, as most of mine tended to be, but it would have to do.

I'd picked up an A to Z some time earlier, and now I drove across north London through the choking rush-hour traffic until I came to a quiet rundown street of cheap 1960s housing. I've got a good memory for facts and figures and I remembered John Gentleman's address from when I'd been round to see him at the apartment block on the night Jenny was kidnapped. Since Tina's last known location was outside Gentleman's flat, I figured it was as good a place as any to start looking for her. Risky perhaps, but I was running low on options.