They say I’m lucky to be alive. But the only thing I can remember are the faces of my husband and baby. The husband and baby they insist don’t exist …

I can hear a door slamming, and the low hum of distant traffic. I struggle to open my eyes, and the panic sets in. I have no memory of who I am, why I’m here, where all this pain is coming from …

Then the door cracks open, a face lighting up in surprise. ‘You’re awake!’ She looks pleased to see me, but all I can think is: I don’t know you. She tells me I’m her sister – that there was an accident and I’ve been in a coma. But as she skilfully evades my questions, I know something is wrong. Because when I ask her about my husband and baby, she gently tells me they never existed. I know she’s lying.

As she leaves the room and the lock clicks behind her, my heart starts to pound. And as the days pass stuck in this room, I start to discover unsettling details I hadn’t noticed before. Photographs that don’t seem to fit their frames. The anonymous note buried deep in a bunch of flowers I feel sure I was never meant to find – with just two words on it: I’m sorry…

What really happened to me? Is this woman really my sister? And if she’s not: who is she, what does she want from me – and what has she done to my family …?