Most eighteen-year-olds are worried about college, relationships, and their future.Blythe Rousseau has a devil named Rosie living in her basement.Blythe has spent her life protecting the world from the red-skinned creature imprisoned in her basement rec room. Rosie cannot be killed, only sedated with a stake through the heart. Invisible to everyone outside her bloodline, the captured monster is both a prisoner and an inescapable burden.After her mother's sudden death, Blythe makes a desperate journey to Winchester, Louisiana, a town that-according to her mother's notes-may hold the key to Rosie's permanent demise and Blythe's first real chance at freedom.Instead, she finds Elsie Audley, the owner of a local cryptid museum and the first person outside her family who can see Rosie too.But in Winchester's moss-cloaked forests and towering cypress swamps, a new threat emerges that Blythe and Elsie must stop together. As Blythe's connection with Elsie deepens and she learns the truth about Rosie's past, she will have to face not only Winchester's monsters, but her own demons.How much is Blythe willing to sacrifice for the girl she loves?