This new release should appeal to the broad audience of middle-grade horror, especially if they've started to grow out of their Goosebumps collection. We have a clueless, but likeable young man who feels like an outsider and it takes being possessed by a demon and on the run for his life to start feeling like he belongs.
Prosperity Redding is a scion of the Redding Family, known for their abundant numbers and wealth. Living in the shadow of the family estate and name and frightened of his domineering grandmother, Prosper's only friend is his twin sister, whose recent popularity means she leaves him to himself these days. Outside his immediate family he is scorned and shunned.
Then, while his parents are away, Proper and his sister find their whole extended family inviting them to their grandmother's house. They are taken down to the forbidden cellar and asked to read from a book. Prosper learns a demon cursed his family centuries ago and his life may be what it takes to save the lives (and fortunes) of his family.
Prosper is rescued from his relatives and in hiding where he learns uncomfortable truths about his family's actions in the past, their consequences, and the workings of magic and other dimensions. The demon offers him everything he ever wanted, not to mention saving his life, if he makes a deal and sacrifices his soul and those of his family. Is his acceptance at his new school, in magical disguise of course, due to the influence of the demon or, when given a chance, can Prosper save his own life and his family and still be a good person?