And then I see it. A dull stain on the tip of one. It’s my sister’s dried blood. I walk over to the edge of the cliff and throw up. It’s the heat, making this worse. I can’t face the rest of my sandwich and I toss it away. And there, hidden beneath the overhang and half-buried in the sand, is a bottle. I pull it out, surprised by its weight, and hold it up to the light. A cork, originally from a bottle of red – maybe one Bethany found on the beach – has been jammed in the mouth; the stub is dyed burgundy. The sun glows through the thick green glass and, even after two days, the contents hiss slightly.

It’s almost full. Bethany had drunk barely a single glass.

So now I know. I stand there, the sun beating down on my shoulders burning my scalp, holding a hot, dark bottle in my hand. My sister was found in the early hours of the morning by a holidaymaker, who called the police. Martelli rang for an ambulance, and the medics carried her on a stretcher round to our beach whilst the tide was still low enough. The Carabinieri did not arrive for several hours. She’d been found with her clothes on, so no one had checked for semen; she had a head injury, so Dr Virgili assumed she’d been attacked and didn’t monitor her blood alcohol. When the Carabinieri came here, they might not have noticed the Prosecco bottle. Even if they had, perhaps they thought she’d drunk it all, or that it was her second.

But I know this is the bottle Bethany took from the house. So now I am certain my sister was not drunk and she was attacked. I am going to find out who did this to her. I owe it to her. She wouldn’t be lying in a hospital bed if I hadn’t accused her of causing Ruby-May’s death. I couldn’t continue to shout at my ageing father and curse his failing memory, so I took it out on my sister.

I can’t help it. I glance back at the bloodied rock. It wouldn’t take much strength to push someone, especially if they lost their footing in the sand and slipped: a disproportionate amount of damage for a small amount of effort. Even a woman could have done it. I think of my other sister, Amy, and reject the idea immediately. Of course Amy would have wanted to kill Bethany, if she’d really been responsible for Ruby-May’s death, but Amy doesn’t have any doubts about her sister. Amy doesn’t know that Bethany lied about taking Dad for a dementia test. Does she?