A family is executed by soldiers for cannibalism - except for the little girl, Katy Bane McKay. She is adopted by Judge Mackay and goes home with him to Canada, where she grows up with no knowledge of her family's past. Then, in the present, several deaths occur and people begin to think it's Katy Bane McKay.

William Munny is a retired, once-ruthless killer turned gentle widower and hog farmer. To help support his two motherless children, he accepts one last bounty-hunter mission to find the men who brutalized a prostitute. Joined by his former partner and a cocky greenhorn, he takes on a corrupt sheriff.