Insidious: Out of the Further

In Pittsburgh, 1999, after her mother, Ingrid, seemingly has a mental breakdown, a young Gemma Hall witnesses her die by suicide in the bathroom before a supernatural force shuts the door.

Two decades later, Gemma, now a single mother and dental hygienist, raises her daughter Maya in her childhood home and is dating Nick, a police officer. While walking Maya home from school, Gemma sees three elderly people walking down the sidewalk. One night, Gemma astral projects and is haunted by visions of Ingrid's suicide. In another projection, Gemma is hunted by one of the elderly people and discovers that she brought back a brooch from the dream.

The next day, Gemma is scheduled to have a cleaning with Lester, one of the elderly people. Lester bites Gemma's finger, causing her to hit her head on the X-ray machine, which knocks her out and sends her into the Further. Gemma wanders the clinic before a blindfolded man restrains her in a chair. Several spirits surround her, and the man chooses one to approach her. Gemma is saved by Elise Rainer, who hands her a book and tasks Gemma with finding her. Using the address in the book, Gemma goes to Abandon, a tattoo shop run by Clare, another astral projector.

Elise temporarily possesses Clare and explains to Gemma that she is a "courier", an astral projector who can transport objects between the Further and the material world. She tells Clare that the blindfolded man is planning to use Gemma to resurrect spirits, and that the elderly people are his acolytes who use sedatives to force themselves into the Further. Gemma tells Nick her situation, who is in disbelief but offers to stay the night. Later, Gemma again astral projects and is attacked by the blindfolded man. He forces Gemma to hold hands with the spirit from the clinic, and she transports half of his body back to the real world.

Gemma spots the acolytes in her neighbors' home across the street. With Nick's help, she sneaks into the home and finds a television playing a VHS tape. Gemma discovers that the blindfolded man is Cyrus Lam, a cult leader who grew his following in the Further by promising resurrection. Clare goes to Gemma's house and communicates Elise's plan: lure Cyrus into a Red Door in the Further and lock him inside, while Nick awakens the acolytes to stop them from projecting.

Gemma and Elise enter the Further and are attacked by two of the acolytes. Nick breaks into the neighbors' home and discovers the owner's corpses. After searching the house, he discovers two of the acolytes beneath the floorboards and wakes them up. The two find Ingrid within the Further, and Gemma discovers that Ingrid was also a courier and had committed suicide to protect her from Cyrus. While rewatching Ingrid's suicide, Gemma slams the door shut on her younger self. Gemma reconciles with Ingrid, and Elise realizes Maya inherited the ability to astral project. While staying at another neighbor's, Maya falls asleep and astral projects, where she is attacked by Lester as Nick is unable to wake him up.

Cyrus uses Maya to bring dozens of his followers to the real world, slowly killing her. Gemma awakes to save Maya, but is overwhelmed by several of Cyrus' followers. Elise possesses the body of Lester and rescues Maya. Due to their failure, Cyrus kills all three acolytes. Gemma is cornered by Cyrus, but she manages to transport the entire house into the Further. The resurrected dead, enraged that Cyrus failed to restore them fully, attack and consume him. Gemma says goodbye to Elise and Ingrid before awakening in the real world and reuniting with Maya, Nick, and Clare.

In a mid-credits scene, Cyrus wakes up in the Further after his attack, where he is restrained in a dental chair and tortured by a ghostly dentist. A key-fingered demon locks them in a cell behind a red door.