At the beginning of the film, a shadowy old woman is seen inside a house while the inhabitants sleep.
Renai and Josh Lambert have recently moved into a new home with their three children. One morning, Renai looks through a family photo album with her son, Dalton, who asks why there are no pictures of Josh when he was a child. Renai reasons that he has always been camera shy and disliked taking photos of himself. One evening, Dalton sees the attic door open and goes to investigate after hearing sounds upstairs. As he enters inside, he tries to climb a ladder to turn on the light, but falls when the ladder cracks. As he falls to the floor, he seems to stare in horror at the darkness as if looking at something terrifying. Shaken, he is put to bed by Renai and Josh and told not to play in the attic because it is off-limits. The next day, Dalton does not awaken from his sleep. Renai and Josh rush him to the hospital, where the doctors say he is in an inexplicable coma.
Three months later, Dalton is moved back to his home while still in a coma. Shortly after, disturbing events begin to occur. The first is when Renai hears a voice on the baby monitor which shouts "I want it now!", a bloody hand-print on Dalton's bed and a strange but frightening man in her infant daughter's bedroom. Renai becomes more disturbed when their youngest son, Foster, says he does not like it when Dalton "walks around" at night. Renai tells Josh about the events, but when she is assaulted by the strange man that night, she begs Josh and the family soon moves to another house. In the new house, the supernatural events continue to occur, such as a strange, dancing boy, and soon become increasingly sinister. Lorraine, Josh's mother, recalls having a strange dream of going inside Dalton's room in the night and seeing something standing in the corner, and when questioned "What do you want?" it replies "Dalton." Subsequently Lorraine sees a red-faced figure standing behind Josh that roars at her and Dalton is then violently attacked in his bedroom. This prompts Lorraine to contact a friend, Elise Reiner, who specializes in the investigation of paranormal activity. The family, Elise, and her team enter Dalton's room and Elise sees and describes a figure to one of her two assistants, who draws a black figure with a red face and dark hollow eyes on the ceiling of Dalton's room; the same figure that Lorraine had seen before in the house.Elise explains to Renai and Josh that Dalton has the ability to astral project while sleeping and that he has been doing it since he was very young. The reason that Dalton is in a comatose state is that he has fearlessly traveled too far into different spiritual worlds (he believes the projections are dreams) and has consequently become lost in a land called "The Further"—a place for the tormented souls of the dead. While Dalton's spirit is in this other world, he has left nothing but a lifeless body. The tormented souls crave another chance at life through Dalton's state, while there are others (possibly the old woman and the frightening man) who are more malicious in using him; the red-faced figure, revealed to be a demon, wants to use Dalton for a more malicious intent. However, for a spirit to consume a body, a period of time and energy is required.
Skeptical at first, Josh later relents when he discovers Dalton had been drawing pictures which resemble the demonic figure Elise described. They run a session to try to communicate with Dalton where the demon uses Dalton's body to fight the group, along with other entities who want Dalton's body. After the session, Elise calls Lorraine and the two reveal to the couple that Josh also can astral project and was terrorized by an evil spirit during his childhood. Lorraine shows them pictures from Josh's childhood, revealing a shadowy old woman (the same woman from the beginning of the film) behind him. The more photographs taken of Josh, the closer the shadowy woman begins to get to Josh until she is inches away from him, explaining his fear of photos. Elise suggests that Josh should use his ability to find and help return Dalton's soul, to which Josh agrees.
To prepare to astral-project and find his son, Elise sits him in a chair and places him in a trance. Josh suddenly awakes to find that he has astral-projected—seeing his own self asleep in the chair as well as the others in the room. He proceeds outside in a misty emptiness in an attempt to find his way to Dalton. After encountering a boy who points him back towards a house (the same home that the Lamberts moved out of), he proceeds, only to encounter a family who is shot by a bizarre female member of the family in the living room. Startled, Josh makes his way to the attic where he discovers a red door (the same one drawn in Dalton's pictures). Before he can enter, the violent man seen by Renai in their daughter's room appears and attacks him. Once defeating him, Josh enters the red door.
Inside is "The Further" and the red-faced demon's lair. While entering a cavernous, red room, Josh discovers a sobbing Dalton, chained to the floor. Josh frees his son, but the demon has discovered Josh's presence and attacks them. In search of their physical bodies, Josh and Dalton flee the demon's lair, with the demon in pursuit. Just before the two awaken, Josh leaves his son to confront the shadowy old woman who appears to be inside his house. As he shouts for her to get away from him, screaming that he isn't afraid of her, she retreats into the darkness. Moments later, Josh and Dalton both awaken, just as all the spirits vanish.
With the family now happily reunited, Renai, Dalton, and Lorraine chat in the kitchen as Elise and Josh pack up from the long night. Josh hands Elise the pictures from his childhood, and as she takes them from his hands, she senses something and takes a picture of Josh. He promptly goes into a rage, screaming that she knows that he doesn't like to get photographed, and leaps on her before strangling her to death. Renai hears Josh yelling and goes into the room to find Elise dead and Josh gone. She searches for Josh and finds everyone is gone, the house dead silent. She looks and comes across Elise's camera, seeing a picture in it of the shadowy old woman. It's revealed that what Elise saw was Josh's old and dirty hand and nails, similar to the old woman's, implying that she has possessed him. Josh then puts his hand on Renai's shoulder, saying "Renai, I'm right here," and horror envelops her face as she looks behind her.
In a post-credits scene, the shadowy, old woman can be seen blowing out a candle and the screen fades into total darkness.
- Patrick Wilson as Josh Lambert
- Rose Byrne as Renai Lambert
- Ty Simpkins as Dalton Lambert
- Andrew Astor as Foster Lambert
- Barbara Hershey as Lorraine Lambert
- Lin Shaye as Elise Rainier
- Leigh Whannell as Specs
- Angus Sampson as Tucker
- Heather Tocquigny as Nurse Kelly
- Corbett Tuck as Nurse Adele
- Ruben Pla as Dr. Sercarz
- John Henry Binder as Father Martin
- Josh Feldman as Young Josh (uncredited)
- Kelly Devoto as Doll Girl #1
- Corbett Tuck as Doll Girl #2
- Joseph Bishara as Lipstick-Face Demon
- Philip Friedman as Old Woman
- J. LaRose as Long Haired Fiend
- Caslin Rose as Ghoul/Contortionist (uncredited)