By the time they come inside, DS May and Sergeant Collins look as though they’ve been standing in the rain for hours. I feel my insides twisting as they take off their coats, accepting my mother’s offer of tea before sitting at the kitchen table.

DS May gets out her electronic notebook. ‘Thank you for talking to us again, Niamh. It’s just that you’re one of a very small number of people Hollie was close to and we need to make sure we haven’t missed something.’

Coming over, my mother places mugs on the table, then pulls out the chair next to mine.

DS May goes on. ‘We’re trying to establish if there might be someone out there who wished to harm Hollie. Did she ever mention anyone she was frightened of? Or had she met anyone new recently?’

Gazing at her, I bite my lip. She doesn’t understand. There are things I can’t repeat, as well as so much I don’t know. The only person who knows what happened is Hollie.

‘I can’t tell you anything,’ I say at last, looking between them.

‘Niamh.’ There’s a warning tone in my mother’s voice.

I turn to her. ‘It’s true. Hollie and I used to watch movies. Sometimes we went for a walk.’ I shrug. ‘She mentioned there was stuff wrong at home, but she never actually said what it was.’

DS May’s frowning at me. ‘Was this recent, Niamh? Hollie telling you something was wrong?’

I nod.

‘And you’ve no idea what it was?’

I try to remember Hollie’s exact words. ‘It was something like she couldn’t trust the one person she should have been able to depend on.’ I stare at DS May.

‘Who was it? A close friend? Family?’

I shake my head. ‘She didn’t tell me who – or why. I don’t know anything else.’ I wonder if she believes me. Then, suddenly, it gets to be too much. Pushing back my chair, I get up and go upstairs.

In my room, I lie on my bed the way Hollie used to – on my back, hands clasped behind my head, staring at the ceiling – before rolling over and pushing myself up with my elbows, so that I can see the window. I’m still lying like that, watching the trees blowing in the wind, when my mother comes in.

‘Niamh, you really shouldn’t have walked off like that. The police need your help.’

I shake my head. She still doesn’t understand. ‘I can’t tell them anything.’

My mother comes over and sits next to me on the bed. ‘Look, I know this is upsetting. But surely you want to help the police find whoever did this to Hollie?’