The movie is based on Miriam Toews's 2018 novel of the same name, which was based on a true story of rapes in an insular, ultraconservative Mennonite community in Bolivia. From 2005 to 2009, nine men in the remote Manitoba Colony, using livestock tranquilizers, drugged female victims ranging in age from three to 60 and violently raped them at night. When the girls and women awoke bruised and covered in blood, the men of the colony dismissed their reports as delusions (even when they became pregnant from the assaults) or punishments from God or by demons for their sins. According to a May 2019 BBC article by Linda Pressly, when the assailants were finally caught, they were arrested by Bolivian authorities. One fled from justice, but the other eight were tried and convicted. Seven were sentenced to 25 years in prison for repeated, multiple rapes; an eighth was convicted for providing the drug, then released. According to a 2013 Vice article by Jean Friedman-Rudovsky, some men and boys in the colony had also been raped, and the druggings and rapes continued after the arrests.
Miriam Toews's book is narrated by the character August Wilson. However, the film is narrated by Autje, speaking to a future child of the colony. Director and screenwriter Sarah Polley said that the film was written and shot with August narrating, but it became clear during the editing process that the story needed to be told by one of the women who had been assaulted. The voiceover also gave Kate Hallett an even greater role.
Explaining the color grading of the film, director Sarah Polley said the filmmakers played with saturation levels to create a feeling of "a world that had faded in the past." This is why the film appears to be almost black and white, but not quite.
Throughout filming, the cast were advised not to put on makeup or shave until wrapping.
Claire Foy was asked to have glued additional hairs to her eyebrows, because her natural (non-plucked) were considered too modern-looking.