The next chapter in the story of Ed and Lorraine Warren.

Ed and Lorraine Warren travel to North London to help a single mother raising four children alone in a house plagued by a supernatural spirit. Anita Gregory, a skeptic, questions the authenticity of the hauntings. The Warrens discover that the demon haunting the house is named Valak. With the help of the Hodgson family, they manage to banish Valak back to Hell.

Paranormal investigators Ed and Lorraine Warren work to help a family terrorized by a dark presence in their farmhouse. As they uncover the history of the house and the malevolent spirit haunting it, they must gather evidence and seek authorization for an exorcism. With the family's lives at stake, they confront the demonic entity and fight to save them.

In 1981, demonologists Ed and Lorraine Warren document the exorcism of 8-year-old David Glatzel. Arne Cheyenne Johnson, the boyfriend of David's sister Debbie, invites the demon to possess him instead. Arne later murders his landlord under the influence of demonic possession. With the support of the Warrens, Arne's case becomes the first American murder trial to claim demonic possession as a defense. The Warrens discover a satanic curse responsible for the possession and investigate further, leading them to an occultist. In the end, the occultist is killed by the demon she summoned.