Grieving mother Mildred Hayes has an axe to grind with the ineffectual police chief of their small town. Determined to get to the bottom of her daughter's unsolved murder, Mildred rents three abandoned billboards near her home excoriating Chief Bill Willoughby and his racist, violent, alcoholic junior officer Jason Dixon. However, unbridled rage yields surprising alliances on Mildred's quest to see her daughter's killer brought to justice.