Seventeen-year-old Karu balances between two lives. She is both an art student and a servant to a monster with ram's horns who acts as her father. Growing up between Prague and Deinde, Karu never really understood Brimstone's dark work buying teeth from murderers. But she wasn't shy about using his magic for her own whims dyeing her hair blue or learning a new language (perhaps not even human). When Brimstone's door closes, Karu must choose between a peaceful life here and a devastating war there, searching for the answer to the most important question of her life: Who am I?