Mexico City circa 1965: Flavia is an aristocratic little girl, who is very lonely and bored. At school she meets and befriends a strange and beautiful girl named Verónica, who dreams of becoming a witch. Their games get increasingly sadistic and macabre, and escalate to involve the bloody murder of a piano teacher and macabre mayhem.—Mateo Monasterio
Ana Patricia Rojo, Elsa María Gutiérrez, Leonor Llausás
IMDB plot
A 10 year old girl convinces a lonely classmate that she is a witch, forcing the child to become her assistant. Though their games are initially rather naive, they gradually take a nasty and violent turn.