Brubaker (1980)
When the new warden comes in disguised as an inmate, he sees firsthand all the corruption and scams the guards and prison officials are running. When he reveals himself and starts to implement reforms to stop the corruption, the local business community, who had been benefiting from the scams, fights back, and the corrupt prison system starts making political trouble for the new warden.
Stars Robert Redford, Yaphet Kotto, Morgan Freeman