In 1981, demonologists Ed and Lorraine Warren document the exorcism of 8-year-old David Glatzel, attended by his family, his sister Debbie, her boyfriend Arne Johnson, and Father Gordon in Brookfield, Connecticut. During the exorcism, Arne invites the demon to enter his body instead of David's. Ed witnesses the demon transport itself from David's body to Arne's while he suffers from a heart attack and is taken to a hospital in an unconscious state.
The following month, Ed wakes up at the hospital and reveals to Lorraine that he witnessed the demon enter Arne's body. She sends the police to the Glatzel household, warning them that a tragedy will occur there. Arne and Debbie return to their apartment located above a kennel where Debbie works. After feeling unwell, Arne murders his landlord, Bruno Sauls, by stabbing him 22 times due to his demonic possession. With the support of the Warrens, his case becomes the first American murder trial to claim demonic possession as a defense, resulting in the beginning of an investigation into David's original possession. The Warrens later discover a satanic curse passed on through a witch's totem and meet with Kastner, a former priest who previously dealt with the Disciples of the Ram cult. He tells them that an occultist had intentionally left the totem, resulting in the creation of a curse on the Glatzels, causing the possession of David.
The Warrens travel to Danvers, Massachusetts, to investigate the death of Katie Lincoln, who was also stabbed 22 times. Detectives had found a totem at the home of Katie's friend Jessica, who is missing. Lorraine initiates a vision to recreate the murder and discovers that Jessica had stabbed Katie while possessed before jumping to her death off of a cliff, which allows detectives to recover her body. The Warrens travel to the funeral home where her body rests, and Lorraine touches the corpse's hand to help find the location of the occultist. Lorraine, in a vision, witnesses the occultist attempting to have Arne kill himself but stops her just in time. Lorraine is threatened by the occultist and she tells Ed that the connection works both ways.
The Warrens return to their house in Connecticut to investigate further. Drew reveals that he has found a book of Stregherian witchcraft which states that for the curse to be lifted, the altar used by the occultist must be destroyed. Ed is affected by the curse, a totem being discovered in a vase of flowers delivered to the house, but is stopped by Drew when attacking Lorraine. When they realize Katie attended nearby Fairfield University, they begin to assume the occultist is operating in the area. Lorraine returns to Kastner for help, and he reveals that he had secretly raised a daughter, Isla, in violation of the requirement of clerical celibacy in the Catholic Church. As he researched the occult, Isla grew fascinated in it, later becoming the occultist. Kastner tells Lorraine that Isla's altar must be in the tunnels underneath the house, leading her into them before Isla finds and kills him. Ed soon arrives and finds his way into the tunnels through a locked drain hole with a sledgehammer. He is briefly bewitched by Isla and attempts to kill Lorraine, but she forces him to recall the time they first met, reminding him of their love. Ed regains his senses and destroys the altar, saving himself, Lorraine and Arne. Isla arrives at her broken altar, only to be killed by the demon she had summoned after failing to complete the curse.
Ed places the cup from the altar in the artifact room, along with the Valak painting and the Annabelle doll. Arne is convicted of manslaughter but ends up serving a sentence of only five years, marrying Debbie while in prison. Ed shows Lorraine a gazebo like the one in which they first kissed.
Directors Michael Chaves
Starring Vera Farmiga, Patrick Wilson, Ruairi O'Connor
Genres Suspense, Horror