'No, but he left me in no doubt that he would if I carried on searching for Jenny. That's why I'm phoning you from four hundred yards down the road. I don't want anyone else listening in.'

'And are you sure you're not being followed now?'

'I'm being extra careful, I promise.'

'Glad to hear it. And don't worry. We can offer you protection if you need it.' But even as she said the words, Tina wondered if they actually could.

Fallon sighed. 'I think I'm going to need it. What did you find out that made you call me?'

She told him about the doctored CCTV footage and the doorman's criminal record.

'So, the bastard was involved.'

'Almost certainly, and that makes it a major criminal operation. If they're going to this much trouble and planning, then there's a very specific reason why they kidnapped Jenny. Her father claims that nothing's happened to her-'

'He's lying. He's got to be.'

'I agree. And I think he's lying because he's under duress, which means the kidnappers are in contact with him. But we still don't know why.'

'It's usually money, isn't it?'

'Usually, but I'd be surprised if it was in this case. I've got some background on Roy Brakspear. He's a widower who lost his wife to cancer five years ago, and he's the director and part owner of a reasonably profitable mid-sized company based in Cambridge which supplies raw materials to the pharmaceuticals and technology sectors. He takes a salary of one hundred and seventy thousand pounds per year and he holds fifteen per cent of the company's shares, which if he sold them tomorrow would net him about three hundred thousand. He's not going to be hitting the poverty line any time soon, but it doesn't make him a rich man. So there's something else, and I think we need to focus on Brakspear himself to find out what it is.'

'What do you need me to do?' asked Fallon, sounding eager to help.

'Right now, nothing. Go back home, get some sleep and leave the investigating to us.'

'Are you going to take finding Jenny seriously now? She's been gone twenty-four hours, and I'm really worried about her.'

'We've got enough evidence to move on this now so, yes, we are going to take it seriously. And I'll keep you informed of progress too, you have my word on that. But I want you to promise me you're not going to speak to anyone about this. Because if you do, it could jeopardize our inquiry.'

Fallon said he wouldn't, and she ended the call, returning to the pile of witness statements for the stabbing on the Holloway Road that afternoon.

It made the usual grim reading. A loud argument between a bunch of school kids, insults thrown, followed by a flurry of fists and feet, then suddenly one of them pulls a knife and plunges it into his nearest opponent. A single stab wound to the chest, delivered without thought of the consequences, and now a fifteen-year-old was in a hospital bed fighting for his life. Tina had never become inured to the casual violence she had to deal with and she found incidents like this – petty, pointless disputes that ended so horrifically and with so much attendant suffering – profoundly depressing. The only positive was that it wasn't going to be difficult to ID the perpetrator. This meant that CID resources could be freed up to look for Jenny. Tina had now decided to speak to DCI Knox about it as soon as she finished her shift. With Jenny missing for twenty-four hours now, time really was of the essence. It crossed her mind to go straight to the Met's Kidnap Unit but she knew they were snowed under with drugs-related cases and probably wouldn't take what she had that seriously. It would be easier if Knox referred it.

She yawned and reached for her cigarettes, deciding that she could probably get away with having one more at her desk, rather than puffing out of the toilet window. But as she lit it she saw an exhausted-looking DCI Knox approaching along the corridor. She'd just thrown the cigarette into the dregs of her coffee cup and deposited it under the table when he opened the door and came inside.

Knox was usually annoyingly upbeat and full of motivational psycho-babble, but tonight he didn't look very happy at all. 'Bad news,' he said wearily. 'Our stabbing's just become a murder. The kid died at midnight.'

Tina's heart sank. Not just because a fifteen-year-old had lost his life and a family would now be grieving, but also because of what it meant for Jenny Brakspear.

Tina would never get the resources she needed now.

When Tina Boyd was nineteen years old and in her first year at university, she was out drinking one night in one of the student union bars with some of the rowdier elements of her psychology course when some bright spark suggested they have a competition to see who could down a pint of lager the fastest. Two minutes later, eleven people – nine men, Tina, and a girl called Claire – had lined up along the bar with their drinks in front of them, while another of the girls acted as timekeeper.

The winning time, achieved by a sixteen-stone rugby-playing former public schoolboy called Josh, was six seconds. Second was Tina, in eight. No one else came close and five of the contestants didn't even finish theirs. Claire ended up with the head spins and had to go home.

That should have been that, but when Josh started bragging about his drinking prowess, Tina's competitive streak kicked in and she offered him a challenge. She would match him drink for drink for the course of the evening, with each of them choosing what to have in alternate rounds. In hindsight, it was a mind-numbingly stupid idea, since Josh was close to twice her weight, but Tina could be like that sometimes. Almost self-destructive in her determination.

Over the next two hours they downed tequilas, sambuccas, pints of bitter, even a Malibu and pineapple (surprisingly, Josh's choice). Tina's boyfriend begged her to stop. She hadn't. Not voluntarily anyway. Eventually she simply passed out in her seat and had to be taken back to her hall of residence, where she spent much of the night throwing up.

The next day, her boyfriend, a slightly built intellectual called Vernon, finished with her, claiming with exasperation that he couldn't go out with someone like her because she was out of control and simply didn't know when to stop. He was right, of course. He could have added that she never did things the easy way, either. It was why she'd got into so many scrapes down the years, both in her police career and beyond. Why she'd once ended up being taken hostage by a gunman and being shot in the ensuing crossfire, cheating death only by the angle of his gun.

But that was also only half the story, because the thing about Tina was she tended to get results. The shot that had hit her in the hostage incident was only a flesh wound and the man holding the gun to her head – the one she'd tracked down herself – was killed. After all the trials and tribulations of her adult life (and there'd been plenty) she was still standing, and she was still catching the bad guys, which meant she had to be getting something right.

So when DCI Knox rejected her request for permission to concentrate on the Jenny Brakspear kidnapping, she'd decided to go it alone. She'd gone to him at one of the few quiet moments in the shift, but as she reeled out what evidence she had it was clear he wasn't really listening. He'd switched off altogether when she was forced to tell him that not only was Jenny's father adamant she wasn't missing, but the man who'd made the initial report had since phoned in to claim that he'd been lying. Tina could understand Knox's scepticism. In the end, policework is a firefighting exercise. You have to constantly prioritize. And cases don't get much bigger than the murder of a schoolboy.