I always thought my demons came out in the day, rather than at night. I’ve never been scared of the dark. I’ve only ever been scared of real things: getting ill, having injections, physical pain… death. Those are my monsters, not ghosts or vampires or whatever else can hide under your bed at night.

I was wrong.

The dark makes everything worse.

When 17-year-old Mary Hades is admitted by her parents to a psychiatric unit, her worst nightmares are confirmed. How can she get better in a place that fills her with dread? Her friendships with the other patients — her wacky roommate Lacey, her protector Mo, and the mysterious, green-eyed Johnny — begin to fill her with hope, until she realizes that people in the hospital are dying without explanation. Something sinister stalks the corridors, and it’s up to Mary to stop it. But the closer she gets to the answer, the more perilous her situation becomes, and Mary discovers the only way to get out alive is to confront the things that scare her most.