And then she stops. The wind shoves us briefly apart as the rain starts again in earnest, pricking holes in the sea, drumming hard against my skull. Cora stares at me. Blinks once, twice, her breath cloudy white between us. Her eyes spill over with tears, and my panic changes, quickens. Forgets entirely about the sea, the storm.

‘Cora—’

‘Where am I?’ She makes a sound, low and distressed, as she spins round in the water, looking out at all that sea.

‘Cora—’

‘I don’t know you. Do I?’ she says. Her voice is high and afraid. Her eyes dull and unfocussed. And there’s something else. Some other change in her – alien and brittle – that I can’t put a name to but understand enough to want to run from. To swim from.

But I can’t. Because it’s Cora. It’s Will mum. And it isn’t her fault that she’s sick, that her brain is slowly destroying itself. It isn’t her fault that she doesn’t know she needs help. And if I save only myself instead, then I’m still the same person who fed my mum enough tramadol and morphine to kill her twice over. I’m still the same person who pretended she didn’t know why she saw a demon climb into her mother’s coffin.

I reach for Cora, pull her towards me with what’s left of my strength. My vision keeps blurring; I’m sinking lower in the water. But to my relief, Cora doesn’t resist this time; she clings to my arm and sags against me as I turn towards the shore. I push forwards, pulling her behind me. As the waves get bigger, the edges of their crests begin to break into spindrift. I have no idea how I’m going to keep hold of her once we hit the breakers, but there’s nothing else to do. Spray stings my eyes, foam blows across my face in streaks. One wave pushes us high, and then together, higher. Cora’s nails dig into my skin, her breath hisses briefly hot against the back of my neck. And then she lunges with a terrified scream – ‘Help me!’ – her hands clamped heavily on my shoulders.

The bubbles of my own scream tickle my face as I struggle to push back up to the surface. Cora’s fear makes her surprisingly – horrifyingly – strong. Her fingers are still digging into my shoulders. In my panic, I keep trying to push up, even though there’s no strength left in my arms. When she lets go for an instant, I give one last shove, and then I’m free again, gasping for air, lungs burning, heart thundering, arms thrashing.

The waves are much bigger now, tossing us around like a giant whirlpool. I can see spinning flashes of the beach, closer now, but still impossibly far. And Cora’s hold on me is even stronger than the sea as she grabs at me with wild-eyed terror. I see her teeth snap together before she opens her mouth to scream again.