His mind focused on Luke Mullen’s father as he walked. On how – Thorne would double-check the month to be sure – he couldn’t have been involved in the 2001 murder case and the hunt for Grant Freestone; the man he’d previously put away for twelve years; the man who had so publicly threatened him.

Because 2001 was the year that DCI Tony Mullen had resigned from the force.

The red Skoda was parked just south of the Bow Road, on a side street below the Blackwall Tunnel approach. Thorne was delighted to see that Dave Holland had arrived in his absence, and, ignoring the DS sitting behind the wheel, he climbed into the back seat alongside him.

The officer in the front seat turned round in a rustle of polyester. ‘Please your fucking selves…’

Though Thorne had talked to Holland from the Mullen house the evening before, they hadn’t seen each other since Holland’s trip to Butler’s Hall. Sitting in the back of the car, they talked about Adrian Farrell, about Holland’s call to Yvonne Kitson and about whether there might be a connection between Luke’s kidnap and the Latif murder.

‘It’s worth thinking about, certainly.’

‘Not for too long though, right?’ Holland said.

Thorne opened one of his cans. ‘I can’t see it to be honest.’

They sat in silence for five minutes after that. Thorne flicked through his magazine while Holland stared out of the window at a view Thorne had already decided was up there with the most depressing he’d ever seen. That said, he wasn’t certain he could stomach the Taj Mahal for four hours at a stretch.

‘It’s fucking lovely round here, isn’t it?’ Holland said eventually.

‘If you like concrete.’

The SO7 man took the chance to jump in, and pointed towards the Bow flyover. The permanently gridlocked slab of granite rose a few hundred yards to the north of them, lifting the A11 above the A12 and carrying traffic across the River Lea, towards Essex and away from the capital. ‘They reckon that’s where the Krays buried Frank Mitchell, you know? Inside one of the supports.’

‘Right,’ Thorne said. ‘1966.’ He knew all about what the twins were supposed to have done with ‘Mad Axeman’ Mitchell, having made the somewhat rash decision to spring him from Dartmoor Prison. Though the Axeman’s final whereabouts remained uncertain, with some claiming that the body had been dumped at sea, it was nevertheless slightly odd that, thirty years after Mitchell’s disappearance, Ronnie Kray’s funeral cortège should have crossed the Bow flyover. It was hardly the most direct route to Chingford cemetery.

The DS looked a little deflated. ‘How come you’re such an expert?’

‘Too much time on his hands,’ Holland explained.

‘At least you knew where you were with those guys,’ Thorne said.

Holland let his head drop back. ‘Nice simple nicknames for a kick-off.’

‘Right. Nobody got confused.’

‘He’s mad, he’s got an axe. What shall we call him?’

‘Er…’

And as they carried on, they could see the man from the Kidnap Unit clocking them in the rear-view mirror, desperately trying to work out if they were taking the piss.

At lunchtime, the Butler’s Hall sixth-formers were allowed to leave the premises for one hour. Some took sandwiches into a nearby park, but most wandered towards the modest parade of shops on the Broadway. They browsed in the small branches of Game and HMV, or hung around outside the fish-and-chip/kebab shop, trying their best not to look like kids from a public school; to avoid getting caught doing anything that might reflect badly on the uniform they wore.

Yvonne Kitson sat in her car at the end of a road opposite the school entrance, watching the kids come out and waiting to get her first look at Adrian Farrell.

Next to her, DC Andy Stone flicked through the Daily Mirror. ‘I still don’t see why you didn’t get DS Holland to come with you, Guv. To point out this little tosser.’

‘Bored, Andy?’

Stone shook his head without looking up from the paper.

‘Dave’s a bit tied up with other things; and, anyway, I don’t want him pointed out. I want to see if I can spot him. Fair enough?’ She moved her thumb back to her mouth, chewed on the nail and stared out of the window.

Most of the time, it seemed to Kitson that you couldn’t have it all; that if your life outside of work was going well, then the job itself would turn to shit. And vice-bloodyversa. A couple of years before, she’d been a high-flyer and she’d known it; the cases had been high profile, just as she’d been when she’d solved them. Then she’d been stupid enough to get involved with a senior officer, and while he had been forgiven by wife and top brass, she had watched both her career and her family life tumble into freefall. Now things were back on an even keel domestically – her kids were doing well, relations with her ex-husband were civil and she was seeing somebody – but work was another matter. Though she was grafting as hard as ever, the job just seemed to grow more maddening with each failure, each compromise. She’d begun to wonder if it might be down to her; if she’d lost the capacity to be satisfied.

Stone stopped whistling between his teeth for a few seconds. ‘This is funny,’ he said. ‘They’re dropping hints in here about some “popular daytime TV presenter” who’s having it away with his male researcher. Who d’you reckon that is, then?’

The Latif enquiry had been as frustrating as any Kitson had known, and every murder case she’d caught since seemed to involve her running headlong into a series of brick walls. The wall she was supposed to be trying to get over that morning had built up around a disturbing rite of initiation into a Tottenham drugs gang. New members would drive around the streets in a car with no headlights on, and in order to prove they were worthy they would have to fire a gun into the first car that flashed its lights at them. It was brutal in its simplicity, in the casually random way that the unsuspecting victim was selected.

The first driver unlucky enough to try and be helpful.

Five days before, having been shot at for no obvious reason, the man behind the wheel of a Toyota Landcruiser had mounted a pavement on the Seven Sisters Road, killing himself and a young woman waiting at a bus stop. One of the city’s newest gang members had moved straight from low-grade crack dealer to double murderer, and though Kitson and the team knew very well which gang was responsible, had spoken to half a dozen young men who knew equally well who had pulled the trigger, nobody was saying anything.

Sometimes the brick walls had wide smiles, and gold teeth, and enough attitude to make Yvonne Kitson want more than anything to punch them into the middle of next week.

She badly needed a result. For the way it would feel, far more than for the way it would look. And now, if Dave Holland’s eyesight and instinct weren’t both seriously screwed, she might achieve one.

Stone turned to the back page of his paper. ‘No real surprise, though,’ he said. ‘I reckon a lot of those TV presenters are batting for the other side, don’t you?’

Kitson mumbled something that could have been ‘yes’ or ‘no’, every committed part of her brain focusing on the group that was crossing the road, and on her first glimpse of Adrian Farrell. On the fact that she owed Dave Holland a very big drink.

‘Is that him?’

Kitson held up a hand to silence Andy Stone, as though the boy they were talking about were no more than a few feet away; as though his hearing were as well developed as his arrogance. She watched him walk slowly down the main road, every bit as hard to miss as she had been led to believe. He was chatting idly with two other pupils, a boy and a girl. Although he would be off the premises for no more than an hour, Kitson watched as he, along with most of those around him, went through the transformation that Holland had described. She watched as Farrell took off his blazer and tossed it over his shoulder; as he loosened his tie.