Set in Lyons in the late 1970s, Rivals deals with the conflict between two brothers on opposite sides of the law. François is a dedicated police inspector, his brother Gabriel is a crook who has just finished serving a prison sentence for murder. Their reunion is not easy but both men want to draw a line under the past. With François's help, Gabriel finds a place to live and a job in a hypermarket. Everything seems to be going well, until the day when Gabriel's criminal past catches up with him...