I can hear the sea now, loud and rhythmic. Insistent. I stop. Wonder if Andrew – if Robert – ever stopped here too, just to listen to the waves crashing against the rocks below.

I take the photo out of my pocket, shine my torch onto his face.

‘What was it?’ I whisper to the wind. ‘What terrible thing did you do?’

Because I know about doing terrible things. I know about guilt. The kind that drags you down like an anchor, all the way to the bottom. And, just like the blackhouse, that can’t be a coincidence either. It can’t be.

‘Why did you stop taking your meds, Maggie?’ Dr Abebe had asked that first day he visited me on the open ward, his too-trendy cologne battling against alcohol gel and floral air freshener. ‘You’ve always been so careful.’

And I’d thought of Mum’s furious, tear-streaked face the day we came home with my first prescription of lithium all those years before. It’s a gift, Maggie! And you’re giving it away – you’re choking it to death. I’d thought of looking down at myself through the wrong end of a telescope – a blurry, tiny me sitting at a grey desk inside a grey room. And feeling the worst kind of jamais vu. As if I were a complete stranger. Someone I’d never seen before.

Did she tell you the good news? Dr Lennon. Those cool, fleshy hands touching mine. A smile hidden behind his big moustache. The latest scan shows significant metastatic regression. The last round of palliative chemo worked wonders, despite your mum’s reluctance. She’ll probably have years instead of months now.

And I’d thought of Mum’s face: thin, white, eaten by shadows. Only that light – that unrelenting light – still bright in her eyes. It’s coming. It’s close. They’re lying. Trust nobody. They all lie. You have to believe me. My arms prickling from the memory of her nails. The pain will send me mad, Maggie. The cancer is coming back and it will send me mad. I know it. I see it.

But how do you tell a psychiatrist in a mental hospital that you stopped taking your meds, that you suffered the first psychotic break of your entire careful life, because you were no longer able to look at yourself in the mirror? How do you tell him that you want to go to a windy, dark island in the middle of nowhere to prove that a man you never met, never knew, was murdered, because that’s the only way that you can see to live with yourself? With what you’ve done?

Because when I articulate it like this – even in my head – I know it sounds crazy. But when they started taking me off the drugs in the Maudsley, when I started emerging from the fog and back into grief and guilt and shame, this place was what I saw. The memory of me standing on that cliff edge in a spotty dress and too-big wellies, finger pointing out to sea, voice full of certainty. A beacon in the dark.