Insidious: Chapter 3 is a 2015 supernatural horror film written and directed by Leigh Whannell in his directorial debut. It is a prequel to the first two films and the third installment in the Insidious franchise. The film stars Dermot Mulroney and Stefanie Scott, with Angus Sampson, Whannell, and Lin Shaye reprising their roles from the previous films.
The film was released on June 5, 2015, received mixed reviews and grossed $113 million against a budget of around $10 million.
A sequel was renewed in June 2016, titled Insidious: The Last Key.
Retired parapsychologist, Elise Rainier, reluctantly uses her spiritual ability to contact the spirit of Quinn Brenner's mother, Lillith, who died a year before. However, she urges Quinn not to make contact with her mother again after a demonic figure continues to haunt her, becoming increasingly malevolent as time progresses and leaving Quinn with her neck injured after the demon flings her around her bedroom. Sean tries to convince Elise, who like him is still grieving after the loss of her husband Jack, to help his daughter, but Elise declines, stating that her previous visits to the "dark" spiritual world made her realize that an evil spirit is hunting to kill her. However, she is convinced by her fellow parapsychologist, Carl, to continue using her spiritual ability, reminding her about her successful case involving Josh Lambert and stating that she is stronger than any spirits or demons because she is living and they are not.
Due to Elise's refusal, Alex suggests to call the demonologists Specs and Tucker, but Quinn's possession grows increasingly worse as she, now possessed by the demon, breaks through her braces. Realizing that they are scammers, Sean prepares to kick the duo out until Elise arrives timely. Deducing that the demon's goal is to lure potential victims to "the Further" so it can eat their life force, Elise decides to enter the spiritual world with Specs and Tucker recording any activities and words she spells out. With the help of a spirit who likewise is a victim of the demon, Elise enters the Further and after a brief encounter with the evil spirit that haunts her, the Bride in Black/Parker Crane, meets with Jack, whom she realizes is the demon. While managing to defeat the demon, Elise returns to the material world after realizing that Quinn has to defeat the faceless version of herself by herself, who is slowly taking control of her features and soul. Though Quinn is at first at a disadvantage, Elise reads a message that the Brenners' late neighbor had tried to tell Quinn of: that Lillith is leaving her with a letter to read before she graduated. Lillith's spirit then appears to help Quinn fully take control of her body and return to the material world. She then disappears after leaving parting words to her family.
Following the Brenner' successful case, Elise decides to come out of retirement and work with Specs and Tucker. She arrives home and notices a figure watching her from outside. Thinking that it is Jack at first, Elise realizes that it is something demonic as the demon suddenly appears beside her.