The Spanish deep south, 1980. The brutal murder of two adolescent girls in a remote and forgotten town in the marshland of the Guadalquivir river bring together two disparate characters – both detectives in the homicide division – to investigate the cases. With deep divisions in their ideology, detectives Juan (Javier Gutiérrez) and Pedro (Raul Arévalo) must put aside their differences if they are to successfully hunt down a killer who has terrorised the community for years.