A horror story based on real events which took place in Burgos, Spain. On Halloween night, teenage Laura, who comes from a deeply religious family, takes part in a seance with a group of friends. When she starts acting strangely, and having scary visions and violent outbursts, her religious mother is convinced her daughter is possessed and the family is introduced to an exorcist priest. He will perform 13 exorcisms on an increasingly weakened Laura before her father realizes something is very wrong.