When the wealthy but lonely young Flavia arrives at her new school in Mexico City, she is quickly befriended by a mysterious orphan named Veronica. What starts out as an innocent friendship quickly turns terrifying when Veronica convinces Flavia she's a real witch and forcers her to become her accomplice. As the line between what is real and what is imagined begins to blur, Flavia and Veronica fall into a spiral of magic, sacrifice, and murder!