Malasaña neighborhood, Madrid, Spain, 1976. While political turmoil ravages the streets all over the country, the Olmedo family arrives in the big city and settles into their new apartment. They soon discover that they are not the only ones roaming its corridors.
After participating in a séance, young Laura begins to behave strangely. Alarmed, her parents ask Father Olmedo, one of the few exorcists authorized by the Vatican to intervene in cases of demonic possession, for help.
After two parents report that their 12-year-old daughter Asunta is missing, the investigation soon turns against them.
