Roseanne McNulty (Vanessa Redgrave/Rooney Mara), a once vibrant and lively beauty in her youth, has spent the majority of her adult life confined to a mental hospital in rural Ireland. She has been institutionalized for so long, no one seems to remember why she was hospitalized in the first place. When a new chief psychiatrist, Dr. Grene (Eric Bana), arrives, he takes a keen interest in Roseanne. He finds a hidden memoir, written over the course of decades by Roseanne, which unravels the mystery of her incarceration, as well as telling the tale of her passionate, yet tortured, life.