Posing as an inmate at a small Arkansas prison, the new warden of the penitentiary, Henry Brubaker (Robert Redford), witnesses firsthand the corruption and abuse inflicted upon the prisoners by the staff. After revealing his true identity, Brubaker brings much-needed reform to the prison with the help of supporters Dickie Coombes (Yaphet Kotto) and Lillian Gray (Jane Alexander). Yet when the benefactors of the old corrupt system are threatened by the changes, Brubaker's battles really begin.