Robin hesitates. He tells himself that this is okay. That they’ll put the evidence to her and she’ll agree to come in for a voluntary interview. But he knows there’s bugger all chance Amy Miller will comply. This is a woman who no comment-ed her whole way through her formal police interview – what are the chances she’ll nod meekly and come with them again? Slim to nothing. But Robin senses Freya’s impatience, and he feels it too.

‘We know you killed him,’ Robin says.

Amy’s eyes narrow. She’s thinking, and glances across to Freya.

‘You’re close, you two?’

‘We’re colleagues,’ Robin replies, blankly.

‘You’re more than that. Have you slept with her?’ Amy directs to Robin.

Freya fidgets beside him but stays silent. ‘No,’ he says firmly.

‘But you know about her and my husband, right?’ Amy says, and Robin thinks, fuck. If Amy tells her lawyer about Freya and Jonathan’s affair, their whole investigation won’t be worth shit. Freya won’t withstand the scrutiny. Nor Robin.

Everything about this is wrong. They’re police. They should leave now, return to the station, wait for forensics, get the arrest warrant and interview Amy properly. In a video-equipped interview room, with her solicitor present. Then they’ll call the CPS, charge her with murder, and she’ll never leave.

But Robin has experience of taking justice into his own hands. He knows sometimes there are situations where there’s no going back. And this is one of those.

‘Tell us how you killed him, Amy,’ he repeats.

She meets his stare, and a smug smile appears on her lips.

‘Let’s say I did,’ she says quietly. ‘Hypothetically. How might it have happened?’

Robin feels a jolt of anticipation. He slowly breathes in, trying to hide his nerves. He thinks about what they found, in the rubbish. The melted plastic bag. The screwed-up tape.

‘You drugged him. And then you suffocated him.’

He feels Freya tense next to him. Keep quiet, he wills her. Keep quiet.

Amy Miller gives a slow nod. ‘Okay, then. Where? When?’

‘In this house. Upstairs.’ There were cameras in the rest of the ground floor, except in the kitchen, Robin knows. ‘And not on Monday. Way before that.’ He watches Amy’s expression, sees a flicker of something cross her face. Amusement? Satisfaction? He’s not sure, but he knows he’s on the right track. ‘Friday night.’

‘Friday night we were at a party with Kal. Everyone saw us, everyone confirmed.’

‘No, Amy,’ Robin says slowly. ‘Everyone saw you. And they were all so drunk by that point, they assumed Jonathan was there too, but he was already dead.’