When a woman's body is found in the Irati Forest, a UCO team is dispatched to the area. This time, Lieutenant Ernesto Selva is working under the command of Gloria Mencía, a young inspector who has managed to gain the trust of Colonel Figueroa. The lieutenant has lost his enthusiasm for his job and is considering leaving the force. However, Ernesto hasn't counted on the addition of Sara Campos, who, after losing Víctor (her ex-partner), completed her academic training and now works as a psychologist in the Criminal Behavior Analysis Section of the Civil Guard. Sara's help will be key, as mysterious murders and disappearances continue to occur in Irati, and for the first time, our investigators are considering the possibility of a new serial killer hiding deep within an immense forest surrounded by stories and old legends.