Vitoria-Gasteiz, Basque Country, Spain, 2019. Two corpses appear in the crypt of the Old Cathedral. Police officer Unai López de Ayala, an expert in criminal profiling, must hunt down the ritual murderer who has been terrorizing the city for two decades.

At the death of his father, Paulo, the youngest son, will have to be in charge of his mentally handicapped brother Daniel. Based on the novel by Bernardo Atxaga.