And then I put it back in the desk and went through the motions – calling an ambulance, ringing Mark, bracing myself for everything that was to follow.

‘Did you ever talk to her about it?’ he asks, his voice hoarse, and I can see how close he is to the edge. ‘Did you ever ask her why?’

‘I tried,’ I say gently. ‘Not straight away. You must understand that I couldn’t do anything that would draw suspicion towards her. I was completely focused on shielding her from that. It felt like a risk even being in a room with her – I was so worried that I would say something to her, or even look at her in a way that would reveal to someone else what I knew she had done.’

‘Even me?’

‘Especially you!’ His eyes flare a little when I say this, but I press on: ‘Melissa was your sister. And Beth – she was always your favourite child. How could I tell you when I knew it would break your heart?’

He bows his head, and his shoulders slump. I see the exhaustion in him, how he is hanging on by a thread. After a moment, he comes and sits opposite me, his eyes scanning the table as if the scuffed surface of it – the site of so many family meals – will reveal some meaning to him in all this.

I did speak to her. Eventually. After the will had been read, and we had discovered that Melissa’s house had been bequeathed to Beth and Beth alone. We had come home, and Eva was in her room, sulking. Mark had gone for a walk, needing to clear his head. It felt like the first time we had been alone – just me and Beth – since the morning of Melissa’s death.

‘She hadn’t spoken much,’ I tell Mark now, ‘after the will was read, and so I asked her how she felt about it, and she just sort of shrugged, like it was no big deal. Her reaction infuriated me. I felt for Eva, the injustice of it, and it annoyed me, Beth’s casual response. So, I told her that she ought to make some recompense to Eva – that they should share the property, it was only fair. And that’s when she looked at me, such coldness in her eye, and she said: Why? Why should I share with Eva?’

I think I spluttered some explanation about righting a wrong, keeping the domestic peace, but my heart was hammering.

‘I said to her then: “Why do you think Melissa left the house to you?” She said: Because I earned it. Such hardness in her voice. She refused to elaborate when I pressed her on it, just clamming up. And when she went to leave the room, I called her back. I had to ask her. I needed to know.’

My heart hammering.

‘Why?’ I asked. ‘Why did you do it?’