A young woman wakes up in a cold, dark cellar, with no idea how she got there or who her kidnapper is. Nearby, the body of another young woman is discovered buried on a remote beach. But the dead girl was never reported missing. Someone has been keeping her alive from beyond the grave. For Detective Inspector Helen Grace it's chilling evidence, that she's searching for a monster who is not just twisted but also clever and resourceful - a predator who's killed before.