The movie is the final installment in the Red Riding trilogy, based on David Peace's novels. It is set in 1983, nine years after the events of the first two movies. The disappearance of a young girl named Ruby has triggered memories in Detective Chief Superintendent Maurice Jobson of a similar case in 1974 where a girl named Clare Kemplay was found dead. The prime suspect in that case was Michael Myshkin, a reluctant and vulnerable young man who was coerced into confessing to the crime.
As Jobson begins to investigate the disappearance of Ruby, he is haunted by his own complicity in the cover-up of the earlier crime. He is wracked with guilt for allowing an innocent man to be imprisoned for the sake of the reputation of the police force. Meanwhile, local solicitor John Piggott becomes convinced of Myshkin's innocence and begins to fight for his release, despite the hostility of the police and the community.
As the investigation into Ruby's disappearance progresses, Jobson is forced to confront his own demons and his role in the corruption and violence that has characterized the West Yorkshire police force for decades. The movie is a grim portrayal of a society plagued by abuse of power, corruption, and violence, and the devastating effects it has on ordinary people.