Kat didn’t plan to be here, on Beth’s doorstep, knocking on her front door. Just like she didn’t mean for the youngest daughter, Ava, to have seen her through the playroom window. But she couldn’t pretend that her standing outside their house was a coincidence after being spotted, so here she is, wondering how the hell she’s going to explain herself.

She should have remembered that watching people is only safe at night, when you can become part of the darkness, a sense of someone rather than a physical presence. But she’d had a restless night thinking about Beth, and how she turned to Saskia rather than Kat yesterday after everything Kat had done for her. By 5 a.m. she was in Jayden and Will’s garage, trying to find the answer in a punchbag. But all she could see – on every wall, and in every direction – was Beth’s face, both now and before.

Kat can hear feet pattering on the wooden floor of the hallway, and the effervescent buzz of children whispering. But the door remains closed. The delay provides a valid excuse for her to walk away, but something is keeping her rooted to the spot. The proximity is feeding her desperation to see Beth, but it’s more than that; a tingle on her skin, a whiff of something not quite right. She looks at her watch. That’s it. It’s past eight o’clock on a Thursday morning and Ava is watching TV in her pyjamas with a cloth tiger in her mouth.

Why isn’t she getting ready for school? And where is Beth?

Fear lurches in her tummy. Has Mark been here? Has he ignored her warning and come after Beth anyway? A thought suddenly blindsides her; could she have made things worse? She rams the door knocker hard against the wood. The whispers get louder, more frantic, allowing Kat to hear the girls’ conversation.

‘I’m going to answer it.’

‘No, don’t! Mummy says it’s not allowed.’

‘Why not? We’re kids. We need help.’

Kat catches her breath. What help do they need? Why hasn’t Beth appeared? Surely she heard the door this time?

‘It could be a burglar.’

‘It’s not. It’s the lady who walks Luna.’

‘Are you sure?’

‘Positive! I saw her through the window.’

Kat pushes her hands deep into her pockets. Adrenalin is flying through her, which she knows from experience means that she’s not completely in control of her limbs. ‘Open up,’ she whispers to the closed door. ‘Please.’

A second later, her plea is answered. The door swings on its hinges and Kat tries to smile at the two nervous-looking girls stood opposite. ‘Hi there, I’m Kat,’ she says in her most upbeat voice. ‘Luna’s dog walker.’

‘We know,’ the older one says. Martha.

‘I told you,’ Ava adds triumphantly.

‘Is your mum at home?’