Explores the relationship between a murderer and a police officer, who pursues him in a duel of life or death. Carapocha helps the policeman.

When the mutilated corpse of a young woman appears in Valladolid, Inspector Sancho foresees a chain of murders. Sancho, with the support of "Carapocha", one of the greatest experts on serial killers, follows the trail of corpses that Augusto, a sociopath with refined tastes, leaves around the city.