Steve Mackleson (Fairbrass) is a violent and dangerous prisoner, incarcerated for double murder in a maximum security prison, and wracked with inner turmoil about his past sins and unquenchable need for carnage. When Marcus (Odubola) becomes his new cell mate, and a daughter he has never met finally requests a chance to meet her estranged father, Steve must reconsider his nihilistic outlook and brutal outbursts. When Marcus becomes the victim of a revenge attack, Steve steps in to save him and they both become marked men, their sentences set to be cut short, the hard way.