Sophie Turner has joined the upcoming HBO Max series The Staircase. She joins Colin Firth, Toni Collette, Parker Posey, Juliette Binoche and Rosemarie DeWitt. Antonio Campos will direct six episodes of the series. Reportedly, the eight-episode series is based on the docu-series of the same name as well as various books and reports about the case of Michael Peterson (Firth), who was accused of murdering his wife Kathleen (Collette) in 2001. He claimed she died after falling down the stairs , but the police suspected he bludgeoned her to death and staged the scene to look like an accident. Turner will play Margaret Ratliff, one of Michael Peterson’s adopted daughters. The Staircase is written and executive produced by show-runners Antonio Campos and Maggie Cohn. Sophie Turner, who rose to fame as Sansa Stark in the megahit HBO series Game of Thrones, will be back on-screen with this new series.