A teenager finds her perfect life upended when she's stalked by a mysterious doppelganger who has her eyes set on assuming her identity. Sophie Turner plays Fay Delussey / Lila Delussey, a high school student cast as Lady Macbeth in the school play, whose father Rhys Ifans is suffering from multiple sclerosis and later diagnosed with bad news, causing tensions within the family. As Fay becomes increasingly haunted by her twin Layla, played also by Sophie Turner, she begins to question her own identity and sanity. The film is a psychological thriller drama directed by Isabel Coixet based on Catherine MacPhail's novel of the same name.