Insidious: The Red Door (2023)

In 2019, nine years after his possession, Josh Lambert's memories of his experience in The Further have been repressed. He is divorced from his wife Renai and his mother Lorraine has recently died. His relationship with his son Dalton who is now 19, has become strained and unpleasant, and he attempts to heal things between them while dropping him off at college but ends with them in a conflict.

In his first art class, Dalton ends up drawing a picture of the red door used to enter The Further. Meanwhile, Josh begins being haunted by the spirit of a man, eventually discovering that it is his father Ben Burton who he believed abandoned his family when he was young. Dalton attends a frat party with his roommate Chris, where he sees the ghost of a student who is constantly vomiting. After accidentally going into The Further again, Chris shows Dalton a YouTube video by Specs and Tucker, explaining how astral projection works, which leads to a clip of Elise Rainier talking about The Further.

Dalton attempts to astral project again while Chris watches over his body. Chris is then attacked by an unseen entity and her screams alert Dalton, who rushes back to his body and sees that it is the red-faced demon that tormented him as a child. After being warned by Chris to stop using his abilities, Dalton calls his brother, Foster, who tells about a recurring dream he used to have of Josh trying to kill them. This spurs Dalton's memory and he finishes his painting, which shows a possessed Josh in front of the red door. A distressed Dalton is pulled into The Further, back to when a possessed Josh attacked them in the basement. He tackles Josh as Josh attempts to kill the younger Dalton and ends up transported back to the lair of the red-faced demon.

Josh begins researching his father and discovers that he killed himself while institutionalized in a mental hospital. He talks to Renai, who reveals the truth about what happened to their family a decade ago and that his father also had the ability to astral project but believed the things he saw were a result of mental illness. Foster shows them a photo of Dalton's painting he texted and they realize Dalton is in danger. Renai helps Josh to go back into The Further to rescue their son.

With Dalton trapped in his lair, the demon possesses his body and attempts to kill Chris but is stopped when Josh manages to find and free Dalton. The demon chases them to the red door and Josh stays behind to keep it shut so Dalton will be safe. Dalton returns to his body and paints over his red door painting with black paint, which in turn seals the real door and The Further.

Josh meets his father's spirit, who guides him back to the living world. Once back, Josh agrees to have dinner with Renai and the kids, hinting at a possible reunion. As he leaves, he unknowingly meets Elise's spirit, who tells him that he has a bright future ahead of him. Josh then drives to Dalton's college, where father and son reconcile as Dalton reveals a painting of Josh carrying a young Dalton out of The Further.

In a post-credits scene, the light over the sealed door to The Further flickers back on.