Beth took two pink shotgun cartridges from her pocket – Eley Hi-Power, I noticed, trying to remember why this was significant – and reloaded the gun smoothly.

‘Get up, Mel,’ she said.

Slowly, without looking at me, Mel got to her feet.

‘Step away from him,’ Beth said.

Mel did as she was told, and Beth snapped the shotgun shut.

‘What you’ve got in your leg is birdshot,’ she said to me, calmly. ‘This load I’ve got here, though, is a double-zero weight. For big game.’ She levelled the twelve-bore at me again. ‘Enough for a deer, or a big cat. Or a man.’

‘Enough for murder,’ I said through gritted teeth.

‘It’ll be self-defence, Joe. You’re twice my size.’

We stared at each other for a moment in silence, the only sound the faint clicking of a bedside alarm clock.

‘Where is he?’ I said, trying to keep my voice level. ‘Where’s Ben?’

She ignored my question.

‘You know our favourite topic of conversation, me and your beautiful wife, these last few months?’

‘Apart from murder?’

‘Our favourite thing was to invent stories about how we could be together. Without any men in the picture. But with our children, and our houses, our money. Without having a couple of messy, complicated divorces. And one night we were both pissed, egging each other on, and I said maybe the best outcome would be if one of you died and the other one went to prison for it. It solved everything in one go. We would get everything and you two would both be gone, and people would feel sorry for us all the time. The sympathy would be fabulous. Then a week ago – Christ almighty – you had your chance. I’m sitting in my car, watching you, thinking Yes, he’s actually going to do it right here in this shitty underground car park, this is literally our dream come true. But you couldn’t even get that right.’

‘Where is he now?’ I asked again.

‘Same place he’s been since Saturday night.’

‘At the country park?’

She laughed.

‘No! We did drive out there but there were too many people around and he was just too bloody heavy to carry into the woods, even with the two of us. So we just left your phone there instead. Then I had a better idea. We brought him home.’

‘Home?’

‘He posted a picture of his own final resting place on Facebook a couple of weeks ago. Spooky or what?’

I frowned, thinking back to all the posts on Ben’s account from the last few weeks.

Building work. Excavation. Foundations.

‘The new summer house in your back garden.’

She raised the shotgun to her shoulder.

‘He loved this house. And now he’ll always be a part of it.’

‘You’ll never get away with this.’

‘We’ve been getting away with it right from the word go.’