I go on like this for what feels like an eternity. Paddling frantically between waves, turning my back on them as they hit, trying not to lose too much ground or choke on too much water. I struggle against a rising panic that has as much to do with watching the beach retreat further and further away as it does the dread of the next wave arriving. The moment I realise that I’ve made it past the worst of them, the worst of the surf, I look for Cora.

Out past the breakers, the sea is rolling, heavy and high. Endless. I struggle to tread water as battling currents push me left and right, toss me up and down. The sea stings my eyes and slaps against my skin. I’m cold now. My jeans feel like a lead weight, my legs and feet are completely numb.

‘Cora!’

For a moment, I can’t see her and I’m scared. The sky is low and dark, the sea is icy. And alive. I’m out of my depth, quite literally – I could be ten feet or a hundred feet from the bottom, I have no idea; the water below me is viscid and black. I imagine stone memorials lining every coast and headland that I can no longer see, and I feel dizzy. I could die out here. Everyone dies out here.

When something brushes my leg, my arm, I scream – thin and high – and I try to get away, kicking out with my legs, trying to turn back towards the shore. Until a hand grabs hold of my shoulder and spins me round.

Cora’s face is waxy white. Her hair hangs in thick wet ropes around her cheeks and ears.

‘Jesus. Thank God you’re all right.’ I pull her towards me. ‘We have to get back to the beach.’

She lets go of my arm, shoves me away. Her face is expressionless. Her eyes blank.

‘Cora, please. It’s not safe out here. We have to get back to the beach. Will and Euan are waiting for us. They asked me to come and get you, okay? It’s Maggie, remember? Please come back with me, Cora. I promise you’ll be safe.’

When she grabs hold of me again, my relief is short-lived. The fingers that squeeze my arm are blue with cold. But the rage in her eyes is white-hot. And then I’m fighting off slaps, as panicked as they are frenzied, aided by furious splashes of water.

‘Cora, stop!’ I put up my hands to restrain her. I don’t want to hurt her, but I can hardly move my arms or legs any more. They no longer feel numb but as if they’re on fire, and spasms of electric pain shoot up into my chest and pelvis. My thoughts – even my panic – feel slow and disordered. I’m running out of time more quickly than energy. ‘Cora. Please. You have to trust me. Let me help you get back to Will.’