I was optimistic; Nick less so. The letter arrived in a crisp, official envelope: could we come and give an interview connected to an ongoing investigation?

‘It’s a different police station,’ said Nick, jabbing at the paper with his finger. We were both starting late that day, and we had newspapers splayed out across the kitchen table, a cafetière of coffee sitting between us. It was like a still life of contented middle-aged coupledom.

‘Yes, silly, it’s Rachel’s local police station,’ I said. ‘They must have spread the web, expanded the investigation. She’s a different council from us, so if they want to involve mental health services…’

‘Lest we forget how good my wife is at telling a story,’ said Nick, with a mirthless laugh, which succeeded in making his remark sound like the exact opposite of a compliment. ‘Mark my words, we need to be prepped for this one.’

I hate Kilburn: I’d begged Rachel not to move there when she’d first rented that nasty flat. It borders the leafy environs of Queens Park, an area I’m happy to cover, but even a couple of streets across takes you into a subterranean hinterland. The police station was no exception, the pavement outside littered with takeaway cartons and dog mess. We picked our way through the debris to the door and asked the clerk on the desk for the Detective Williams who’d written the letter.

We waited at least ten minutes before a dishevelled woman shoved her way through the crowded waiting area towards us.

‘Mr and Mrs Appleby?’ she said.

I sprung to my feet, stuck out a hand.

‘Yes!’ I said. ‘Detective Williams? It’s a pleasure to meet you.’

She took a beat before she responded, eyes subtly flicking up and down. I’d come from a viewing and was wearing a new pair of black wedge heels with a fitted aubergine dress that skimmed my Pilates-toned body before falling to the knee. I knew in an instant – particularly looking at the way she was futilely pretending that her bobbly black jacket matched her shapeless trousers – that I should have made myself less threatening.

‘Do follow me through,’ she said with a smile that failed to reach her eyes.

My skin began to prickle. I’d been anticipating sympathy and vindication, but perhaps Nick was right to be on high alert. I comforted myself: in a way, it confirmed that we were a good team, filling in the gaps for one another.

She led us to a windowless interview room, a white Formica table like a butcher’s slab dominating the space. We sat down opposite her, but she didn’t utter a word for a few seconds. Ordinarily I’d have grabbed the bull by the horns, but I knew enough from my lawyer husband to know that we shouldn’t speak first. It was more than that, though – she was somehow owning our collective silence.