In February 2018, the casting began, with Matt Smith cast to play Manson, and Hannah Murray, Odessa Young, Marianne Rendón, Merritt Wever, Carla Gugino, Kayli Carter and Suki Waterhouse among the supporting cast. Chace Crawford and Sosie Bacon were cast in March 2018, with Gugino no longer set to star in the film. Annabeth Gish joined the film in April.
