‘That’s a lie too!’ Kat screams, turning back to face Beth. ‘If Martha knows which recipe your mother-in-law uses, there’s no way you don’t.’

‘Beth?’ Saskia’s hoarse, tired voice crackles through the air and both Beth and Kat turn towards it. Her face is still puffy, but there’s some colour in her cheeks now. ‘You fed me nuts on purpose?’

‘Of course not, darling. I would never do that. Thank God you’re okay.’

‘Yes she did. You were too close to working out the truth.’

‘Ignore her – she’s crazy,’ Beth says, her voice settling. ‘You know that; you’re the one who warned me about her.’

‘She saved my life,’ Saskia whispers.

‘It all happened so fast,’ Beth pleads. ‘She threw concrete through my window; I would’ve looked for your EpiPen if I wasn’t distracted by that!’

‘You found my phone, didn’t you?’ Kat continues, trying to recapture Saskia’s attention. ‘And told Beth about it. That’s why she changed her mind on the doorstep, hugged you, invited you inside.’

‘Yes, but so what?’

‘Beth never hugs anyone, does she? She hates touching people – you know that. That’s how desperate she was to get my phone off you.’

Saskia pauses a moment, realisation mixing with confusion. ‘But it incriminates you, not her.’

‘Did you look at the photos?’ Kat asks.

‘Yes, you strangled Mark,’ Saskia croaks, but there’s no fear in her voice. Perhaps her body is too weary for that.

‘I mean properly look at them,’ Kat presses. ‘I was there, but it was Beth who attacked him. After Mark approached Ava at school, and Simon called the police, I knew she’d try something, anything, to get rid of him. So I followed her.’

‘That’s madness!’ Beth laughs, but it sounds more like a cackle. She must realise it too because her hands fly up to her mouth.

‘Did you see the previous photo, Saskia, the one of Beth?’

‘I saw all of them.’

‘But did you look carefully?’ Kat keeps on. ‘See where she was, or check the timestamp?’

‘No, I …’ Saskia’s eyeline shifts to the opposite sofa, and Kat follows it. There’s a dark shadow between the off-white cushions. It’s her phone. She lurches towards it, but Beth is faster, spinning on her toes, and swiping the phone before Kat reaches the sofa.

‘That’s mine,’ Kat says. ‘Give it back.’

‘Why, because it’s got evidence that you strangled Mark?’ Beth asks, her eyes blazing now. ‘And that you’ve been stalking me, taking photos, making voice recordings, for weeks?’

Kat turns back to Saskia. ‘She’s twisting things; I promise she’s the dangerous one.’

‘But you followed me too, didn’t you?’ Saskia says, her voice the quietest. ‘I felt it at the time, on the common. And I was right, because there are photos of me.’