After being court-martialed and stripped from his rank, General Irwin (Redford) is sentenced to a maximum security prison, called the Castle, run by an iron fisted warden, Colonel Winter (Gandolfini). Although Winter respects the once great general, the feeling soon fades as Irwin constantly confronts him on his methods on running the prison. Each time Winter tries to tighten his grip on Irwin, the ex-soldier becomes more defiant.
Meanwhile, Irwin's defiance rallies the other inmates who wish him to lead a revolt against Winter and take control of the prison.