The Book of Secrets is a series of stories following the Exurrana in a world known as Paradox. The first story is known as The Book of Black Sheep, and follows a girl named Jade Exurrana. As she becomes an adult, she finds a peculiar black cat outside of her car after school on a rainy day and takes it home. A day passes and she wakes to find that the cat has turned into a person, and her mother starts explaining The Other Side to her, the world where Jade was born. She explains that angels and demons exist, but are human like with the exception of their universal magical ability. They're also gender locked, angels female, and demons male. She tells Jade that she's the only female demon in existence, and has potential. So Jade is forced to throw her normal human life away to work with a group of angels that hunt monsters known as fallen. Upon Jade's first encounter with a fallen, memories start occurring to her, memories of a dream she's had her entire life. She starts remembering the woman she talks to every night, and after being cursed with horrific nightmares Jade starts out on her own to find this woman.