The Jack Bull tells the story of Myrl Redding (John Cusack), a Wyoming horse trader who clashes with Henry Ballard (L.Q. Jones), a fellow rancher, after Ballard abuses two of Myrl's horses and their Crow Indian caretaker, Billy (Rodney A. Grant). When a local judge throws out Myrl's complaint, the war he wages to force Ballard to nurse the emaciated animals back to health escalates into a vigilante manhunt, murder, and the possible defeat of Wyoming's bid for statehood.