In the end, I could torture myself no more. Sitting alone in a poky flat, wallowing in the guilt of depriving kids of their father, was always going to be a recipe for disaster. So when the film finished, and the couple who hadn't been able to stand the sight of each other at first predictably got together and disappeared off into the sunset, I went to bed. It was a measure of my exhaustion that I was asleep almost before my head hit the pillow.

Most nights my sleep is a blank space where nothing happens, but that night was different. I dreamed of many vague things and woke up time and time again. Everything was a jumble, a messy kaleidoscope of images and thoughts and memories that for split seconds were ice cold in their clarity, but just as quickly faded like dying film heroes as I moved on to the next one.

Only one dream stayed in the mind. It came in the grey time just before dawn. In this dream, I was in a television studio watching an edition of Family Fortunes. I was up in the audience, but the audience was just a blur. The studio was very dark but there was a light that shone on Les Dennis, so you could see him well enough, and I remember that he was wearing a pink suit with a lime green shirt. Les was introducing one of the families but I couldn't make out their name because everything was too dark. He spoke to each of them in turn, and as he stopped in front of an individual player a light shone down on that person so you could see who was who.

First there was the driver of the Cherokee, Paul Furlong. He only had one eye, the other was just a bloody mess where I'd shot him, but he looked happy enough, and he laughed when Les told a joke. Then there was the front-seat passenger, Bayden-Smith. He still looked morose and most of the top of his head was missing. When he spoke, his voice sounded slow and drawling like a record on the wrong speed, and it took me a couple of seconds to work out that this was because his jaw was hanging off his face at an odd angle. I remember thinking that I was glad he didn't have kids. Then there was the back-seat passenger, but I couldn't really see his face very well and he kept looking away. Les tried to put him at ease by saying that he'd heard he was a very good skateboarder and inviting him to elaborate. But still he wouldn't look at us. Miriam Fox, who was standing next to him in a slinky black dress, her throat sliced from ear to ear, put a protective arm around his shoulders.

'You're Miriam,' said Les.

'That's right,' said Miriam in a pleasant voice.

'And what brings you here, Miriam?'

'I'm here with the dead.'

'Here with the dead!' laughed Les. 'That sounds good!' And he looked at the audience, and they all laughed too. 'And who's this?' he added, looking towards the person on the other side of Miriam.

I couldn't see who it was because the light wouldn't shine on her and she was silhouetted in the darkness, but I had a dread feeling of familiarity. She was small, smaller than Miriam, and I thought I could make out curly hair.

'Is it your sister?' asked Les, still smiling, and Miriam suddenly looked very sad, as if Les had touched upon some secret tragedy. She started to say something but the words didn't come out or, if they did, I didn't hear them.

There was a long pause, and the audience fell silent.

Then Les turned back towards us, and he too looked troubled.

'These are the dead,' he said.

And then I woke up, sweating and frightened.

'Miriam Ann Fox, aged eighteen, died from a single stab wound to the neck delivered from behind. The wound was almost two inches deep, suggesting that it was a) a very sharp bladed knife, and b) a very strong person delivering the fatal blow. From the angle of the wound we can surmise that the perpetrator was considerably taller than her. She was five feet three; he, and I think we can safely assume it was a he in this case, is almost certainly between five feet ten inches and six feet two. The victim either bled or choked to death as a result of this one wound. The pathologist thinks that the perpetrator held her up while she choked and died, then laid her out on the ground on her back, before stabbing her four times in the vaginal area.'

'So he didn't have sex with her then?' asked one of the assembled group.

It was 8.35 the following morning and Malik, me, and the fourteen other detectives assigned to the Miriam Fox murder hunt were sitting in the incident room while DCI Knox, the official head of the investigation, stood next to a whiteboard giving his summary of what we knew so far. Welland sat next to him, but was once again not looking himself. If someone had asked me for a diagnosis of his condition I would have said his batteries had gone flat, which seems to happen more and more to coppers of a certain age, and I wondered briefly how much longer he was going to last on the Force.

No such concerns about Knox, who was a big charismatic guy with a deep, resonant voice that swept across the room. 'There's no evidence that she had sex either immediately prior to or immediately after her death,' he continued. 'According to the pathologist she died at some point between eight and ten on Sunday night. Now we've spoken to a number of the girls who work the area and she was seen by at least two of them at about eight p.m., which was when she generally started her shift. She spoke briefly to one of the girls, and the girl said that there was nothing untoward about her. She then moved down the street to her usual spot, which is the corner of Northdown and Collier Street, and from there she was picked up by a car – a dark blue saloon, we haven't got the make yet – and driven away. Usually the girls try to get the number of the cars but, sod's law, no-one did this time.'

There was a resigned murmur from the assembled men, including me. You don't expect to get too many lucky breaks in the course of your work, but on a case like this you need a few.

Knox paused to take a sip from his tea. 'They didn't drive very far though, as we know. The victim was killed at the spot where she was found. As the crow flies that's no more than a few hundred yards from where she was picked up. It's important we trace this car. We've got a dozen uniforms who are going to be doing house-to-house in the vicinity to see if anyone can remember seeing a vehicle fitting the description near the scene. If we're lucky' – more groans – 'somebody might even have got a look at him. He would have been heavily bloodstained after the killing. We're checking CCTV on every possible site from where she was picked up to where she was discovered, but so far nothing's turned up.'

'None of the toms recognized the car, then?' asked Capper, who was a DS, the same as me. I didn't like Capper; never had. He had an unpleasant haircut and constant bad breath, but I wouldn't have held those things against him particularly, not on their own. It was the way he sucked up to senior management I didn't like.

Knox shrugged. 'They see a lot of dark-coloured saloons in their line of business so no-one remembers this one.'

'You said that the toms tended to make notes of punters' registration plates.' It was me speaking this time.

'That's right.'

'Do they ever keep records of them?'

He shook his head. 'No, it doesn't appear so, not according to any of the girls who were spoken to last night. We still might get the number, though. We'll be appealing for information on Crimestoppers and in the area itself. Boards'll be going up round there this morning, so someone's memory might get jogged. We need to find out if she had any punters who she went with on a regular basis. Most of them usually do. We've got two statements from girls testifying that she was picked up on more than one occasion by someone in a red TVR, although no-one ever saw his face. Apparently she had a friend, a girl by the name of Molly Hagger, who used to work the streets with her – I believe you've got a photo of her, Dennis – but she hasn't been seen for several weeks.'