Spain was in the midst of a great transformation in the early 1980s. There was a remote town in the swamps of the Guadalquivir River Basin, where an extremely cruel murder of a young girl took place. Detective Padro (Raúl Arévalo) and his partner Juan (Javier Gutiérrez) from Madrid were ordered to investigate the matter. However, the murder case was not as simple as the feudal and conservative local residents thought. The two gradually discovered that this was a serial disappearance of young girls. They were probably facing not just a cruel murderer, but an organization. With the key clues provided by the victim's mother (Nerea Barros), the case became more confusing. During the investigation, Padro also discovered Juan's unknown past. What was even more disturbing was the corruption of society and the poverty and indifference of the people in the town. Both faced great challenges.