On February 12, 2005, Sister Dorothy Stang, a Catholic nun and environmental and social activist, was gunned down in the Brazilian rainforest in which she had lived and worked for over 30 years. The trials of the gunmen and the rancher accused of arranging for her murder sent shockwaves through the environmental community, exposing the politics surrouding the battle over the future of the rain forest and the plight of the peasant farmers who live there. Stang, who was born in Dayton, Ohio, but became a naturalized Brazilian citizen, had fought and worked on behalf of the farmers of the region for decades, working with the Brazilian government to establish sustainable living communities that would allow poor farmers to survive while preserving the natural habitat from excessive deforestation.

Filmmaker Daniel Junge followed Stang's brother David to Brazil, to make They Killed Sister Dorothy, a documentary about Stang's lifework and the effort to bring her killers to justice. The filmmakers also had unprecedented access to the defendants and the defense team, allowing them to show both sides of the story. Sister Dorothy's perspective is told largely through interviews with those who knew her best: the peasant farmers among whom she lived and work, her fellow Sisters of Notre Dame, who lived and worked with her in Brazil, the federal prosecutor who was her friend and ally, and Sister Dorothy herself, through archival footage.