The story begins with a prologue entitled "Eleven Years Ago", in which Wendy recounts her sixth birthday party. She expresses contempt at the gifts of fragile porcelain dolls she does not want. She throws a tantrum at seeing her mother has bought her a chocolate birthday cake, to which her mother asks what sort of child she is. Wendy's mother claims she is not her daughter, and attempts to take her life with the knife she had been using to cut the cake.

In the modern day, we see Wendy as a troubled young woman who struggles in school and has forced her brother, Matt, and aunt, Maggie, to uproot their lives and move away when she is expelled from school yet again. She soliloquises that she has a power of persuasion and thus demonstrates on a threatening teacher. She approaches the mysterious and fellow new-student Finn Holmes after class and asks why he always stares blankly at her.

The two start an odd friendship until Finn confronts her about her using persuasion on a classmate. He then reveals to her that he is a member of the Trylle, a tribe of trolls who live as a community in Minnesota called Förening. He tells her that he is a Tracker, and insists on returning her to Förening. Wendy refuses until two members of a rival Trylle tribe, the Vittra, attack her and attempt to kidnap her. Finn intervenes, taking her back to Förening.

There, Wendy meets her real mother, Elora, who informs her that she is actually the princess of the tribe, and is the highest rung of society. She meets Rhys and Rhiannon, both something the Trylle call "mänsklig".

Whilst wandering the halls of the Palace, Wendy breaks into a locked room stocked with many undisplayed photos. She recognizes in one of them a sad Elora with a male baby, then realizes one contains herself, wearing a white gown and an injured leg, an horrified expression on her face. Finn discovers her and tells her that Elora's Trylle power consists of precognition that she can only utilise through painting. Finn tells her of the societal rules of the Trylle; whilst the Princess, Queens and Marksinna (nobles) are the highest, the Trackers and mänsklig are considered even lower than the peasantry.

Finn reveals that Elora and his father had once had an affair, to which Wendy expresses disbelief that Elora could show an emotion other than anger.

Finn begins to tutor her in the history and etiquette of the Trylle so that Wendy can properly handle her future role as Queen and not embarrass Elora. He warns Wendy that she cannot become involved with Rhys passed a platonic level as it would "corrupt" the bloodline of the royalty, and the strong powers held by the royals would cease to exist. Finn reveals that the mänsklig are the children taken in place of the changelings, that live with the family who swap the children, and Rhys is the mänsklig left in Wendy's place.

An introductory ball is scheduled to be held in Wendy's honour which Finn prepares her for. Elora tells Wendy that she will be choosing a more appropriate name for her Trylle life. Wendy says that she does not want to and will not, much to Elora's annoyance. Elora speaks with Finn and he resigns. Wendy finds him before he goes and the two share a kiss. Finn says that he cannot allow her to proceed.

The next night at Wendy's ball, the Vittra attack, forcing the Trylle that possess helpful powers to retaliate. Jen, the member who had previously injured Wendy when trying to kidnap her, rounds on her. Rhys attempts to help her escape but is knocked unconscious. Finn returns, almost losing his life to aid the princess. Tove, a young Marksinna, uses psychokinesis to save Finn's life and successfully get rid of Jen.

Elora and the Trylle inside the ballroom manage to quell the Vittra threat and the three return inside. Finn and Wendy reunite, until Elora informs Wendy that Finn has left, having been transferred once more. Wendy reacts angrily and uses her persuasive powers on Rhys to get him to drive her home to Matt and Maggie, his biological family