Ronald Fraser and Paul Massie star in this comedy prison drama. New inmate Rainbow (Massie) has just been imprisoned for a year for his part in a fight over his girlfriend Wendy (Carole Lesley). After being assigned to kitchen duty, he becomes involved in a food-trading racket. When the scheme is betrayed to the prison's governor (Paul Rogers), its prime mover is threatened with an extended sentence - unless Rainbow can come up with a way to save him.