When she left the station just after six that morning, walking exhausted into a bright orange dawn, the name of the murder suspect was already known; it was now simply a matter of building the case against him. Tina could leave her colleagues to deal with that. More important for her was to formulate a plan to gather more evidence to get either Knox or the Kidnap Unit interested, because one way or another Jenny Brakspear's time was running out.

As she drove the short distance home, smoking a cigarette, she knew she was going to need to sleep first, otherwise she'd be useless. But Rob Fallon could still make himself useful.

It was time to give him his wake-up call.

'There's been a change of plan.'

'What's happened?' I asked, squinting against the brightness of the early-morning sun. It was 6.45 a.m. and I was walking down my street in the direction of the park, having been woken from an extraordinarily deep slumber ten minutes earlier.

'I can't get the help I need on the Brakspear case.'

'Why the hell not?' I asked, wondering what you had to do to get police assistance these days.

'One, we've got a murder inquiry on, and that takes precedence. Two, we still haven't got any concrete proof that anything's actually happened.'

I started to protest, but Tina cut me short. 'Listen, Mr Fallon, you're preaching to the converted. I don't like it any more than you do. But for the moment, we've just got to accept that we're on our own.'

This was the second occasion on which I really should have told her about what had happened to Ramon. The fact that he'd been killed in my house would definitely get police attention. The problem was, in the absence of a body, or indeed even a suspect, it might be attention of the wrong kind. Once again, it would be my word against everyone else's. Maybe even Tina wouldn't believe me this time. So I kept quiet about it. 'OK,' I sighed. 'So what do we do now?'

'I think Roy Brakspear's involved, and he's operating under duress. We need to find out why. When I phoned him early yesterday morning, he was at home. What I want to do is plant a listening device inside his house.'

'Is that legal?'

'Let me worry about that. I know someone who can get me the kit I need but it'll probably take me some time. In the meantime, I want you to drive up there.'

'How do you know I've got a car?'

'I checked you out, Mr Fallon. It pays to know who you're dealing with.'

You had to hand it to her. She was coolly efficient – the kind of person both Jenny and I needed. But it was still vaguely disconcerting to discover how easily she could access the details of my life.

'I want you to do some low-level surveillance of Roy 's home – I'll email you the address and directions. That means finding a spot where you're not going to look conspicuous or out of place, and watching it. I want to know if he's there or not, and if he is, if there's anyone there with him. He drives a silver Audi A4 saloon. If there are any other cars parked on his property, or just outside, make a note of their numbers and call me back with them straight away. I haven't got a clue about the layout of the place but if you feel you can get close to the house and have a look inside, do it, but on no account get yourself caught.' Her tone hardened. 'Do you understand that? Do nothing too risky and make sure your phone's turned off. And something else too: I'm putting my neck on the line for you here, so if the shit hits the fan and you get caught trespassing, don't mention my name. If you do, I'll deny we ever had this conversation.'

'What are you going to do?' I asked, feeling weirdly like one of the characters in my old book, Conspiracy.

'Get a few hours' sleep, then I'm going to track down those listening devices.'

'If you do manage to plant one and you find anything out, how are you going to tell your bosses without getting yourself implicated?'

'I'll think of something,' she said evenly. 'I always do.'

She took my email address and hung up, leaving me wondering what kind of police officer I was dealing with. I was hoping above all else it was one who got results, because otherwise it wasn't just Jenny's life on the line.

It was mine, too.

The Brakspear family home was an imposing detached house on the edge of a village not far from Cambridge that must have been pretty once but which had recently had a business park tacked on to the end of it. I drove past the front entrance but the security gates were closed and a high redbrick wall on either side prevented me from seeing much beyond, so I drove on another hundred yards and parked in a quiet tree-lined lane running off the main road.

It was ten past ten, the journey having been an extremely slow one thanks to heavy traffic on the M11. No one had been tailing me, or if they had they were damn good at it, and I felt a renewed sense of determination as I got out of the car and breathed in the fresh country air. At last it seemed I was actually doing something worthwhile in the hunt for Jenny, and if I could do anything to bring to justice the bastard who'd murdered Ramon, any risk I took would be worth it.

But they weren't the only things driving me. It was also the feeling that, after years of doing little more than existing, unsure about what direction I was heading in, I was finally actually living again.

Although the front of Brakspear's house faced the business park (which I imagine must have pissed him off when it was built), this was partly compensated by the fact that the property also backed directly on to an open field, which bordered the lane I'd just parked in. I climbed over the fence and made my way along its outer edge until I came to the wall at the back of the house. It was lower here, just over head height, with thick, impenetrable-looking leylandii hedges looming on the other side.

I was reluctant to trespass, particularly as there was no obvious exit route, but it was also clear that I wasn't going to find out anything from where I was standing. I tried the back gate but it was locked. So, checking that my mobile was switched to silent, I took a couple of steps back and did a fairly decent impression of a running jump, hauling myself over the top of the wall and sliding down the other side, getting scratched and snagged by the foliage all the way. It wasn't the most dignified of entrances, and I had to crawl on my belly commando-style under the hedge in order to poke my head out the other side.

The garden was mainly well-kept lawn with a stone patio running along the back of the house, complete with a table and chairs and a large Australian-style gas barbecue. It wasn't as big as I imagined and only about twenty yards separated me from the patio doors. They were shut, as were all the windows, even though the day was sunny and already warm – twenty degrees at least. There was something else too. The curtains were drawn behind all but one of the windows on the ground floor, which seemed odd, especially if Brakspear was there.

I lay where I was for several minutes, watching the one window with no curtains for any sign of activity inside, but there was nothing, and I quickly found myself becoming bored. I've never been the patient type, so I crawled out from under the hedge and, staying on my belly, made my way over to a neatly trimmed waist-height privet hedge that ran along one wall towards the house. I got to my feet and, using it as cover, walked, crouching, towards a wooden gate that provided access to the front.

I paused for a moment, listening for any sound coming from the other side. I heard nothing, so I slowly opened the gate. There were two cars in the driveway. One was Brakspear's Audi A4. The other was a dark blue Mazda. I took a couple of steps forward so I could read the number plate and took a photo of it on my mobile phone.