The book’s main character, twelve-year-old Oscar, is a shy boy used to loneliness. At school, they torment him, and hating his tormentors, he invents a “pastime”: he goes alone into the woods with a knife and takes out his anger on trees and rotten stumps, imagining they are his pursuers. But one day, one of his classmates is found in the woods with a slit throat, and the circumstances of the crime are extremely suspicious—everyone is convinced it was a ritual murder.
Not long before this, Oscar gets new neighbors—a father and a daughter who move into the neighboring apartment building. And although at first the girl has no interest in talking, soon Oscar and Eli become best friends. Yet there is something strange about her: she tolerates the cold far too easily, she jumps far too well, and—most importantly—she goes out into the yard only when night falls.
Eli’s relationship with her father is no less suspicious. Is he even her father? Who is she, and what connection does she have to the chain of ritual murders that has shaken the whole city? Over time, Oscar finds answers to all these questions, though—perhaps—he would have preferred to remain in ignorance.