In a small town in Missouri, Mildred Hayes' life takes an unexpected turn after the brutal rape and murder of her daughter, Angela. Desperate for justice and frustrated with the lack of progress in the investigation, Mildred decides to take matters into her own hands. In a bold move, she rents three strategically placed billboards along the road leading into town, on which she delivers a provocative message to Police Chief Willoughby and the community at large.