Bridget pushes her arms into the sleeves of her leather jacket. ‘Wait here,’ she says to Toni. ‘He’s in Ham. I’ll be there in ten, fifteen minutes tops.’

‘But how do you know he’s there?’ Toni is crying.

‘He left his Friends app on. I can only think he must have thought he’d swiped it off, but it didn’t stay off. That happens sometimes on iPhones, but whatever, I’ve got him, I’ve fucking got him, and I’m going to get her right now.’

‘No,’ Toni wails, her face red and shining with tears. ‘We’re calling the police now, Bridge. Come on, it’s time.’

‘But I’ll be there before them, Tones. I’ll be halfway there by the time they’ve even picked up the phone. I’ll have her in my van before some dick in a uniform can find a fucking pen. She’s in fucking Ham, Tones – it’s ten minutes away.’

Toni is shaking her head, sobbing. ‘No, Bridget.’

Bridget crouches down in front of her sister and takes her hands. ‘I get it. I do. But just… just… Look, give me an hour, can you do that? One hour. If you don’t hear from me in an hour, we’ll call, OK?’

They lock eyes. Both know what they see reflected there: themselves, the pact, and everything that has rested on it ever since. Even the fact that Bridget is here now, at her broken sister’s side, where she has been since that terrible summer’s day when all their lives were turned upside down.

‘One hour,’ she insists. ‘But I’ll be less.’

Toni sniffs. ‘I’m coming with you.’

Oh Christ.

‘No.’ Bridget stands, grabs the keys for the van from the hook by the door. ‘Think. You’ll only slow… you can’t… we need someone here in case… what if she comes back? The police would make you stay here, because you’re her next of kin. Trust me. You’ve got your phone. Keep it close to you. I’ll be in touch.’

‘Fucking hell!’ Her sister’s face crumples. She bangs her fists on the table, bashes them against her head. ‘I feel so helpless, Bridge! I feel so fucking trapped!’

Bridget kisses her sister’s cheek and presses her lips to her ear. ‘You’re not helpless. We are not helpless. You’re the one who saw the wood when all I could see were the trees, remember? And I drive faster. We’re a team, so keep it together, yeah? I’ll call you once I’ve got her. After I’ve cut that motherfucker’s balls off with a rusty knife and made them into a key ring, all right?’

Before Toni can argue the toss, Bridget runs from the house. The van starts first time and she cries out with triumph. She is wired. She can’t believe her luck. The bastard must have given his location in the early days to create trust, all part of the grooming, all part of the I’ll show you mine if you show me yours. Sick, sick, sick. Did he know he’d left it on? Did he mean to cancel and forget? Or did he do like she does sometimes with her mobile data – think she’s swiped it off and then a day later realise it’s pinged back without her knowing and she’s had it on 3G by mistake all this time and run up a nice fat extra cost? It doesn’t matter. What matters is the motherfucker is now a flashing circle. It may have the cheesy too-good-looking face of Mr Raoul Mendez in it right now, but pretty soon Bridget will be planting her fist into another face entirely. It won’t be the first time she’s beaten up a man.

‘Come on,’ she shouts at the windscreen, at traffic too slow too slow. Come on; come on. She is going to find her niece and bring her home. She will leave whoever that bastard is sorry that he ever messed with her family. This whole situation is surreal. She can barely believe what she’s doing. When she installed the tracer app, never did she think she’d be using it like this. She thought it’d be for one of the million times Rosie left her phone at Naomi’s house or between the sofa cushions or at the bottom of her school bag. Not this – never this.

But the bastard isn’t far, not far at all. It won’t be long now. He’ll wish he’d never been born.

She steers the great hulk of the van through the lights. The green banks of the Thames to her left, the water churned and brownish, she drives as fast as she dares: sailing through T-junctions, gritting her teeth at pedestrian crossings, taking mini roundabouts on two wheels. But by the time she reaches Hampton Wick, the traffic is at a standstill.

‘Fuck!’ She slams her fists into the steering wheel.

There are roadworks, temporary traffic lights. It was all going too well. Bridget chews at her thumbnail and swears prolifically at the road.

She fumbles for Rosie’s phone, checks that the tracker is still showing the same location. It is. The bastard is still there then.

I’m coming to get you, she thinks. I’m going to make you wish you’d never laid a hand on her.

With a surge, the traffic moves forward. Bridget throws the phone into the hollow by the gearstick, makes it, last, through the lights and is filled with insane joy.

‘Come on,’ she shouts, to no one. ‘Come on!’

Kingston town centre is torture. Saturday afternoon: can people think of nothing better to do than buy stuff? Lobotomised sheep, the lot of them. But if the traffic is moving slowly for her, it has moved slowly for that sick bastard too, and she will track him down like a bloodhound tracks a wild boar. She will track him down and rip his—

The traffic moves.

‘Come on,’ she shouts, overtakes, undercuts.

The sustained, angry blare of a horn. The cars slow and halt once again. With a cry, she bangs her back against the seat and thumps the steering wheel. Calm. Calm down. Focus. There is no way she’d be this close if they’d called the police. They’d still be waiting for some dope to process the call. Those photos are still on her laptop. At least Tones won’t see them on Rosie’s phone. But would they incriminate Bridget if the police saw them? Pictures of an underage girl, even if it is her own niece? Oh God, they might be sick enough to think that. You can’t trust the pigs. You can’t trust anyone it seems to her now in her sudden loneliness, the cold despair of her van.

Only family.

Through Kingston at last, left, along, and the common rears up on her left. She takes the corner too quickly, the van lurches, she fights with the steering wheel to right herself. Three more turns and she’s there, the road lined with neat terraced cottages, flowers in their front gardens, twee as fudge tins. This is the edge of the estate; the back gardens of these little houses must give onto the main road that runs between here and the ragged terrain of the Ham Lands. Her eyes dart, searching for a space big enough. She should have brought Toni’s little runaround but she can’t bloody drive the thing. A space, maybe ten metres away. Heart pumping, she parks. Jumps down to the pavement. Checks her phone. Runs.

She is close. She is there. She is standing in front of a whitish terraced house in a poor state of repair, the window frames peeling, rotten wood. Wild flowers, weeds and long grass spring from the front garden; inexplicably, there is an upended office chair with a wheel missing. The sun is hot on Bridget’s back, but she zips up her jacket all the same. An extra skin. Only now does she think about protecting herself, that she should have brought a knife, a baseball bat.

A gun.