Peggy Hodgson, a single mother, and her four kids live in a house with a sinister history. Situations get out of hand, and the threat of life looms constantly over the family members.
Paranormal experts, Ed and Lorraine Warren, take charge and attempt to eliminate the evil before it destroys everyone involved.
In 1975 Amityville New York, Ed and Lorraine are investigating the infamous Amityville House one year after the grisly murders of six members of a family.
While in the house, Lorraine experiences a series of horrific visions including one where she witnesses herself as the committer of the Amityville murders. Lorraine screams in fear when sees a demonic nun briefly appear and impale Ed.
Three years later in Enfield, England, the Hodgson family is experiencing paranormal events. The second daughter of the family, Janet Hodgson, exhibits signs of being possessed by a demon. Her behaviour deteriorates – she plays with the Ouija board, sleepwalks abnormally, and converses with an invisible entity.
The reports of Janet being possessed quickly spread in the media. Ed and Lorraine are requested to offer their assistance to determine whether or not the case is true.
Due to the visions she experienced, Lorraine is reluctant for Ed to get involved as she fears something bad might happen to him. Ed, however, convinces her, and they both reach the Hodgson’s house.
At the Hodgson’s house, the Warrens are prepare for the investigation. However, before they get started, they contact other paranormal experts who covered the case to get an idea of what they are dealing with.
They obtain a tape that shows Janet deliberately sabotaging the kitchen. The Warrens figure the Hodgsons are staging the whole paranormal charade for fame. Therefore, they decide to leave.
Despite the video recordings proving the haunting was fake, Lorraine isn’t completely convinced. Lorraine has another vision where the spirit of the previous owner of the house is taken away by the nun.
She immediately realizes the demon took away her ability to detect the demonic presence. The Warrens rush back to the Hodgsons’ house to resume the rescue effort.
They find possessed Janet locked inside while the rest of the family is outside. Ed somehow manages to get inside only to find Janet prepared to commit suicide. He saves her just in nick of time.
Lorraine finds her Bible with the demon’s name, Valak, written on it. She addresses her by her name and condemns her to go back to hell. Valak disappears leaving Janet and her family in peace.