She grinned. ‘This is all a bit sudden…’

‘I know what was wrong with the video,’ Thorne said. ‘What was bothering me.’

Porter leaned back against a large chest freezer and waited to be told.

‘It’s all to his mum.’

‘What is?’

‘Everything Luke says on the tape is aimed at his mum. He says nothing at all to his dad. I’ve got a transcript in my bag and I checked. Have a look if you like-’

‘I believe you. Go on…’

‘Try not to worry, Mum. Nothing to get yourself worked up about, Mum. You know the stuff I mean, Mum. Everything’s for her. It’s like Mullen’s being cut out.’

Porter thought about it. Behind him, Thorne could hear the boiler clicking and then the rush as the pilot ignited the gas. ‘Maybe Luke was punishing his father,’ Porter said. ‘For the argument they’d had.’

‘It must have been one hell of a row, then, don’t you think? If the kid’s still bearing a grudge while he’s being held hostage. While he’s being tied up and drugged.’ Thorne moved across and settled in against the freezer next to Porter. She shuffled along to give him room. ‘Anyway, I talked to Luke’s sister, and she’s positive the row wasn’t that serious.’

‘I think you’re reading too much into it.’

Thorne shrugged, acknowledging the possibility.

‘Like you say, the boy’s in trouble. So you’re probably right – he’s not likely to be thinking about whether he’s fallen out with his dad – but it’s perfectly natural for him to be thinking more about his mum, isn’t it? He’s only a kid.’

‘Maybe. He’s obviously trying to be brave for his mum because he doesn’t want her to worry. But shouldn’t there have been something, some message, for his dad? Everyone keeps banging on about how close they are.’

‘He didn’t mention his sister, either.’

That was a good point. Porter had a disconcerting habit of making them. ‘It feels strange, that’s all,’ Thorne said.

‘Maybe he didn’t have a lot of choice about what he said.’

This was something Thorne hadn’t considered. ‘Are you saying it was scripted? You think he was told what to say? It certainly didn’t feel like that.’

‘Just thinking aloud,’ Porter said.

They stopped at the sound of footsteps on the other side of the door. They listened, heard the fridge door swing open, and Thorne waited for whoever was helping them-self to leave before he spoke in a whisper. ‘Let’s keep thinking,’ he said.

Porter’s mobile began ringing as they stepped out of the utility room; just when Tony Mullen walked into the kitchen. Mullen stared, his face giving nothing away, while, for reasons he couldn’t immediately fathom, Thorne felt himself redden.

Mullen nodded towards the phone in Porter’s hand. ‘I think you’d better get that,’ he said.

Porter answered, said nothing for a few seconds, but Thorne could see that whatever she was hearing was important. He glanced across at Mullen and could see that he knew it, too.

‘Right,’ she said. ‘When?’

Thorne stared until he’d made eye contact, and saw nothing but concentration.

‘I’ll get back as soon as I can.’

Mullen stepped forward, asking the question calmly as soon as she’d ended the call. ‘Have they found him?’

‘Mr Mullen…’ Porter glanced at Thorne, then hesitated further when she saw Mullen’s wife appear at her husband’s shoulder. ‘I’m sure you understand-’

Maggie Mullen clutched at her husband’s sleeve, asked him what had happened. He didn’t take his eyes off Porter, and when he spoke his voice was no longer quite so calm. ‘And I’m sure you understand. So let’s hear it.’

Porter took a second or two, then spoke quickly. ‘It’s good news,’ she said. ‘Apparently the people holding Luke aren’t as clever as we thought they were.’ Her eyes flicked to the screen on her phone, as if searching for more information, before she dropped the handset back into her pocket. ‘We got a good set of prints off the videotape.’

‘You’ve got a match?’ Mullen said.

Porter nodded. ‘We’ve got a name, yes.’ She turned to Thorne. ‘And we’re working on an address.’

Investigating a murder rarely allowed those involved much of a private life, but the hours devoted to a kidnap case were even more brutal. For those few he’d been given to get his head down, Thorne was offered a room at a small hotel in Victoria where the Met had a permanent block booking, but he decided to make the trip back to Kentish Town instead. The travelling would cut down his free time between shifts, but he wasn’t sleeping much anyway. He preferred lying awake at home to wearing out the thin carpet of an anonymous hotel room; to dunking teabags on strings, listening as the city coughed itself awake, and worrying about the fact that he hadn’t fed the cat.

Perhaps if it had been a slightly nicer hotel…

He arrived home just after midnight, still early enough to call Phil Hendricks. Five minutes into their conversation and the last can of Sainsbury’s lager, he was starting to relax. To enjoy telling his friend about the celebrated criminal history of a man named Conrad Allen.

‘So he waves this plastic Magnum around…’

‘I presume we’re talking handgun here as opposed to ice-cream…’

‘I’m not listening,’ Thorne said. ‘He waves it around, comes on like a hard case or whatever, thinks that’s an end to it. But, unfortunately for Conrad, the other bloke’s a little bit pissed off. He gets straight back in his car, dials 999, and fifteen minutes later an armed response unit’s squealing up and Dirty Harry’s face down on the Mile End Road, trying to convince some very pumped-up coppers that he was only having a laugh.’

‘So how come he never got done for it?’

‘Ask the CPS, mate. He was charged, but when it came to taking it any further, I suppose they just decided it wasn’t worth the effort. But, luckily for us, he was fingerprinted and this was back in 2002 before they changed the law, so the prints never got destroyed after the charge was dropped.’

‘What, and the silly bastard just forgot you had them?’

‘Forgot that, forgot to wear gloves when he was handling the videotape…’

‘Not the sharpest knife in the cutlery drawer.’

‘I don’t think this is his usual line of work, you know?’ Thorne thought about another tape he’d seen a few hours before, back at Central 3000. ‘Some of the boys on the Flying Squad are fairly sure Allen’s the bloke who turned over half a dozen petrol stations and off-licences in Hackney and Dalston last year. Him, another gun that’s probably plastic, and a woman, pretending to be a hostage. A lot of shouting and shit acting.’

‘Sounds like an episode of EastEnders,’ Hendricks said.

‘It’s a jump from that to kidnapping kids, though, don’t you reckon?’

The tape of in-store CCTV footage had been biked over to the Yard from Finchley. As he’d watched, Thorne had struggled to equate its images with those on the tape that had been sent to the Mullen family. The picture of the big man in the ski-mask – the violence in his movements and language – failed to gel with that of the figure who’d walked towards Luke Mullen with a syringe. That action was equally violent, every bit as brutal, in its own way, but Thorne simply couldn’t see Conrad Allen moving so easily on to something so clinical.

Something so quietly vicious.

Instead, he’d found himself watching the woman: staring at the screen as she screamed and begged for her life, pleading first with the robber and then with each terrified cashier and shop assistant to hand over the money before she was killed. If the man with the gun to her head was Conrad Allen, then the chances were that she was the woman who’d charmed a sixteen-year-old boy into her car. She might not be the greatest actress in the world, but Thorne had little trouble believing what she might be capable of. It was easier to imagine her as the driving force, as the one who’d come up with a way to make a lot more money than could be grabbed from the average till. Why she’d targeted Luke Mullen was a totally different matter…