Luna, a teenage student from Madrid, manages to convince her parents to let her spend the summer with her aunt Emma, an enigmatic woman who she has not seen since childhood. Once there, Luna discovers that her aunt is a sorceress with real powers, a descendant of a long line of witches that goes back for centuries. While Luna begins to learn the secrets of magic, without much success, her aunt confesses that for weeks she has felt somebody trying to get into her mind to read her thoughts. Despite having used her most powerful spells against this being, she has not managed to get rid of it....