It's the week before Halloween and Char’s mother, Angela, has inexplicably disappeared. All that remains is her abandoned car. When she returns home without explanation the following evening, it becomes clear to Char and her grandmother, Rita, that something is amiss. She might look and sound the same but Angela’s behaviour has become increasingly frightening, as if she has been replaced by a malevolent force. When Halloween arrives, a night steeped in ancient myth and legend, Char realises that she is the only one who can save her, even if it means potentially losing her forever.