Mary’s in the shower after a long day’s work when the lights go out. Her phone screen flashes in the dark. The text is from an unknown number:

‘You’re not alone in this room.’

When she wakes up, her head is pounding and there’s a churning in the pit of her stomach. She’s lying naked on the cold hard floor of a room she’s never seen before. The door is locked.

There’s a deep cut across her thigh. The key to the door has been sewn into her leg. It’s the only way out of this room.

Detective April Fisher must race against time to catch a killer in a sick game of cat and mouse.