When the body of a teenage girl is found on the banks of the River Baztán, it is quickly linked to a similar murder one month before. Rumours are flying in the nearby village of Elizondo, Is this the work of a ritualistic killer or is it the basajaun, the 'invisible guardian' of Basque mythology? Inspector Amaia Salazar leads the investigation, taking her back to where she hoped never to return, the heart of the Basque country. Shrouded in mist and surrounded by impenetrable forests, Amaia must fight the demons of her past to confront the reality of a serial killer on the loose. But as she is drawn deeper into the investigation, she feels the presence of something darker lurking in the shadow. Spanish thriller starring Marta Etura, Elvira Mínguez and Carlos Librado 'Nene'.