Prosperity Redding is the only unexceptional member of his very successful family - that is, until he discovers a demon living inside him. Turns out, Prosper's great-great-great-great-great-something grandfather made - and then broke - a contract with a malefactor, a demon who exchanges fortune for eternal servitude. Now Alastor, the malefactor, has reawakened and is intent on destroying the Redding fortune, unless they can kill him in the body he inhabits - which, oh, wait, that's Prosper, and why is his grandmother coming at him with a silver blade? In danger from both the demon trying to take over his soul and the family that would rather protect their fortune than their own kin, Prosper narrowly escapes with the help of his long lost Uncle Barnabas and Barnabas's daughter, Nell, a witch in training. According to Barnabas and Nell, they have only days to break the family curse and find a way to banish Alastor back to the demon realm. Until then, Prosper has to deal with Alastor's vengeful mutterings inside his head (not to mention his nasty habit of snacking on spiders). And, every night, Alastor's control over his body grows stronger. . . As the deadline to the curse draws nearer, Prosper and Nell realize there's more at stake than just the Redding family fortune. . . that there might be something else out there, something worse than Alastor, that could destroy the balance between the human and demon realms and change the world as they know it forever.