NOTE: This spoiler was submitted by Spectre.
We open in the bedroom of Renai Lambert (Rose Byrne). She wakes up to her husband Josh (Patrick Wilson) lightly snoring. Unable to go back to sleep she goes downstairs and reaches for some books in a moving box and puts them on the shelf. Renai sits down, thumbing through a photo album. She smiles at her wedding photo. Her son, Dalton comes down and says he couldn't sleep as well. They look at photos, and he asks to be shown a picture when he was young. Just then his infant sister Callie cries. Renai sighs and says "At least you didn't cry as much as your sister."
At the breakfast table when see Renai and Josh have three children: Dalton, Foster, and Callie. Josh comes down and says he has to stay at school late and thus cannot take or pick up the kids from school. Renai asks him if he has seen her box of sheet music but Josh says he hasn't. Renai looks for something in the living room to find her books strewn from the shelf. She tells Dalton he has to put the books back where he found them. But Dalton denies ever touching them.
Later in the day, Renai works at the piano trying to compose a song when she hears Callie crying. She goes upstairs to comfort her when she hears some creaking from the attic. She puts Callie back to bed and investigates. The attic is dark, and the light is barely out of reach. Renai has to step on a ladder (which one rung breaks) to get the light. She looks around but finds nothing. She shuts off the light and goes downstairs.
Later at night Renai is in the living room with Foster and Callie. Josh comes home and gives a gift to Foster telling him he has to share with his brother. Meanwhile, Dalton is playing alone when he hears noises in the attic. He cannot see and reaches for the light, but has to climb high on the ladder. The previously broken rung breaks further and he tumbles to the ground, knocking his head. He looks around and hears a strange clicking noise...
Downstairs Josh is playing with Callie when they hear Dalton scream. Josh and Renai tell Foster to stay with his sister while they investigate. They find Dalton in the attic and lightly scold him for playing in a dangerous area. As she is about to go downstairs, she looks to the other side of the room and sees her box of missing sheet music which puzzles her. In the end though, they are glad Dalton is OK and put him to bed. Rose tells Josh they need to lock the attic so the kids won't go up there. She notes that her missing sheet music turned up in the attic, and she didn't put it there.
The next morning, the family is at breakfast, but Dalton hasn't come down. Josh goes to wake him up, but he realizes something is wrong. Dalton is not responding. He tries to shake him to no avail.
Dalton is in the hospital. Josh and Renai are told by the doctor that the scans showed no damage, but their son is in a coma. The doctor has not seen anything like it before. They plan to do more tests but for the moment there is nothing they can do.
3 MONTHS LATER
Dalton has been released for in home care. Josh and Renai are briefed on how to take care of their son. It is clear they still don't know what is wrong but will not give up. Renai at this point is beyond broken and wants it to end.
Renai is trying to work on her music but her heart is clearly not in it. The baby monitor begins to crackle static but its not Callie. It's another voice barely a whisper. Renai turns up the volume, but can barely make it up. Suddenly, the house is shook with a thunderous voice saying, "I WANT IT NOW." This frightens Callie and Renai races up to comfort her daughter.
Josh is spending more and more time at school, grading papers. It is clear that he is trying to avoid his problems.
The next night, Renai is tucking her other son Foster in. Foster asks to switch rooms. Renai asks why and Foster says he doesn't like it when his brother walks around at night.
Later, Foster tries to sleep, but cannot when he starts to hear creaking noises. He looks across the hallway to see his brother in the bed and closes the door. With the door closed, the moving around intensifies. Foster is scared and falls under the covers of his bed.
Meanwhile, Josh hears a knock at the door and goes to investigate. The lights cut out so he uses a flashlight to look through the curtains to see no one out there. He deadbolts the door and sets the security alarm. Renai hears Callie crying and goes to investigate. When she looks into the nursery, she sees a figure in the windowsill, which freaks her out. She screams for Josh but by the time he comes the figure is gone. Just then the security alarm goes off. He tells Renai to get the kids into Dalton's room while he looks around. He goes downstairs and sees the door wide open and the deadbolt chain unlatched. He wanders room to room but finds nothing. He shuts the door and reactivates the alarm.
The next day, the nurse comes to check on Dalton. Renai wonders if all this is a test to see how far she can go before she will break. The nurse consoles her telling her that the forces "messed with the wrong woman." Renai begins to adjust Dalton's covers but sees blood at his feet. Taking out the creases, she realizes it is an animal like hand print.
Renai waits up for Josh outside when he comes home. Renai tells him that she is afraid for her son and Josh is avoiding the problem like he always does. Josh denies he is avoiding the problem. Renai shows him the hand print and tells him to "handle this."
That night, Josh is sleeping on the couch. Renai wakes up and sees he is not in their bed. She sees a figure outside their window pacing. She thinks for a moment for Josh and calls out to the figure. The figure then stops then looks at her. It then appears in the bedroom and begins to attack her. She screams and Josh races up to find his wife cowering in the corner. Renai tells him that something attacked her and pleads for him to believe her. Josh asks what she wants him to do. Renai says she wants out of the house, they need to leave. Josh agrees and holds her close.
Josh and Renai move into a rental home to get away from their house. Josh's mother Lorraine (Babara Hershey) comes by to help unpack. She tells Renai she needs to take it easy and no one is judging her for what she is going through because no one can understand. Lorraine says she should do whatever is necessary to get through it.
Later that day, Renai plays some music on a record player and takes out the trash. A young boy is out of her eyesight who proceeds to make the record scratch and change the song which Renai notices outside. She sees the boy dancing in the living room and races in to find the place empty. She then sees him in the hallway laughing, running into Dalton's room. The room looks deserted but she then sees shoes peeking out of a crawlspace. She investigates and is startled when the ghost boy races by her laughing.
Josh comes home and finds Renai and his mother talking to a priest. They sit down later and Lorraine tells him that Renai is not crazy because she is experiencing the same thing. She had a dream where she was at their house and went to Dalton's room where a dark figure was in the corner. Lorraine asked who what he was. The figure replied, "a visitor." Lorraine asked what he wanted. The figure pointed at Dalton and said "HIM."
As she is done telling her story, she looks to her son, and sees a devil figure right behind him, which startles her out of her chair. The three hear a large bang coming from Dalton's room and find it in shambles. The bed is torn apart and adorned with more bloody hand prints and Dalton is on the ground, but still alive. Lorraine says she knows exactly who to call.
Two paranormal experts come to the house. Specs (Leigh Whannell) and Tucker (Angus Sampson). Specs is more friendly and Tucker is eccentric, more concerned with his equipment. While Specs talks to Josh and Renai Specs uses a device to tests various shades of UV lighting. He seems to find nothing wrong until the third try when he sees two ghost women smiling at him. Taken aback, and realizing this is not a false alarm, Tucker tells Specs they need to call Elise NOW.
Elise (Lin Shaye) arrives and gives Lorraine a hug. It is clear they have know each other for a long time. Elise asks to look around the house and the group follows her into Dalton's room. Seeing something on the ceiling fan, Elise begins to dictate while Specs sketches what she is describing. Renai wants to know what is going on and grabs the sketch book and sees what Specs drew: A large devil like entity, all black and a blood red mask.
Elise tells them since they called they must at least be open to what she has to say. They have to move quick so she's just going to tell them. Their son is gifted in astral projection, also known as out of body experiences. Dalton has been journeying every time he has slept. Only this time he went too far and got lost in a realm called "The Further", a realm that holds the souls of the damned. All they want is to live again and will use Dalton's body to do it. However, the devil figure has only one agenda; to take Dalton's body and do serious harm. In order to get Dalton back, they have to a seance to guide his soul back to his body. However, Josh has had enough and doesn't believe any of it, thinking Elise and her team are trying to con them out of money. He sends them away despite Renai's protests.
Josh talks to Dalton and asks him if he is away somewhere. Josh dismisses that saying he is right here with him but he needs a sign. A paper falls behind him and Josh looks at it. It's the picture of the devil spirit. Josh looks another where Dalton drew himself saying he watched himself sleep and then flew away. Josh breaks down and cries because he realizes Elise was right. Renai comes in and Josh agrees to do what Elise thinks is best.
The next night they get ready for Elise to go into the spirit world. She puts on a special gas mask which has a funnel into a pair of earphones that Specs wears to dictate. They have several cameras to set off flashes with any changes in temperature and lighting. Josh and Renai are told not to say a thing while it is happening.
As Specs dictates, Elise calls out for Dalton. She asks him where he is, and to come towards her voice. Dalton responds that she has to be quiet or "they'll hear her." Elise persists and Dalton then says they heard her. Dalton goes silent then Elise begins to shudder and hyperventilate, quickly speaking in a different voice that promises to tear out her innards and calling her a bitch. In the meantime, Dalton's EKG is spiking off the charts. Elise finally relaxes, free from the spirit world just as Dalton flat lines. Josh and Renai look over shocked as Dalton rises from the bed and smacks the table, causing a force blast that throws everyone to other sides of the room. The cameras are flashing like crazy at this point, as Specs and Tucker are attacked by spirits. Renai is held by the throat of the ghost that attacked her before with Josh unable to stop him. Elise grabs onto Dalton and tells the spirit to leave him. It finally does, causing Dalton to collapse back to his coma, and bring the room back to normal.
Elise calls Lorraine over and explains they know each other so well because Lorraine called Elise to save her son...Josh. Josh is also skilled astral projectionist that passed it to Dalton. Josh doesn't remember any of it, so Lorraine shows him some photos. In each an old woman was stalking him, until it looked as if she was ready to take over his body. Lorraine called Elise and drove the spirit away. Through memory repression and preventing photos being taken of him, they stopped the spirit. Now, however, Josh will have to go into "The Further" if he wants to find Dalton's soul and return it to his body.
Josh is prepped by Elise and begins to drift off. He then gets up, saying it didn't work only to stare at his body. He leaves the house and walks outside with a lamp, into a foggy nothing. He sees nothing but darkness in every direction. Then, out of nowhere he sees his son. Dalton points in one direction, and Josh looks to see the house they previously lived in. Josh goes inside.
Inside he sees an old woman (the same one from his youth) go up the stairs. He calls to her but she doesn't respond. Josh hears a strange whistling. He goes into the living room to find a father reading the newspaper with his daughter sitting next to him. His wife is ironing next to them and none of them are saying anything or responding. He goes into another room to see another girl and asks about his son. She doesn't respond.
Suddenly, Josh hears gunshots. He goes back to the living room to see the second daughter murder her entire family. He turns to leave, to find all four standing up "alive" and grinning horrifically at him. Josh races up the stairs.
He goes up to the attic, where he finds a red door (like one his son drew). He is about to go in when the spirit who attacked his wife begins to beat him up. In the real world, the group can see Josh struggling so Elise says for Josh to remember that he is stronger than all of them because he is still alive. Josh is able to force push the spirit away and goes through the door.
Josh now finds himself in a bright red hallway, lit by candles. He goes further and finds a large room where Dalton has been chained up hostage. Josh hugs his son and says he is here to get him out here. Dalton says he has to be quiet because the monster is here. We see the devil spirit listening to an upbeat song while he files his nails sharp with a sewing machine. He stops his work and looks at the two. Josh unlocks his son from the restraints and they run out of the house back into the fog. They don't know the way however, and the various spirits are crowding them, trying to possess them.
In the real world, Renai calls to Josh and tells him to follow her voice. Josh and Dalton find the house but have to go around to the back. Elise tells Specs and Lorraine to check on Dalton. Josh and Dalton get inside and Josh tells Dalton to go ahead. Josh is about to follow when he sees a figure and says "You?"
Dalton tries to get to his room, but the devil monster breaks through to the other room. Dalton tries to hide in his parents room but the spirit finds him. The spirit tries to grab him but Dalton gets away, with the monster not far behind crawling on the walls.
In the real world, the spirits are starting to break through and the entire group can see them. They have to keep lights on Dalton and Josh despite their fear at all costs. Specs and Lorraine realize that Dalton has woken up and is back to normal. But Josh is still in the spirit world.
Josh is looking at the Old Woman spirit from his youth. Josh tells her he isn't afraid of her anymore. She smiles but is pushed away. Just as several spirits reach out to take Josh's body, he comes back from the dead. Josh and Renai hug and Elise and her team smile, the mission a success.
Specs and Tucker pack up the equipment and talk about how Tucker wants to write a book about what they do. Lorraine, Renai, and Dalton are in the kitchen while he eats spaghetti. Dalton says he is hungry and tired despite his coma. Renai lovingly and jokingly says he won't go to sleep again and she will hold on to him.
Josh thanks Elise for her help saying she showed him "a new world." Elise counters saying he has been there before. Josh hands her the old photos from his youth saying he doesn't need them anymore. Elise says she will destroy them but notices something is wrong. She quickly reaches into her bag and grabs her camera. She takes his photo and looks at the result which horrifies her. This makes Josh snap, asking why she did that when she knows he hates it. He begins to choke her to death, his voice turning demonic, calling her a "fucking bitch." It is not Josh. He has been possessed.
Renai, hearing the commotion, goes into the living room to find Elise dead. Shocked, she searches the room for Josh but doesn't find him. Renai finds the camera and is shocked by what she sees. A flashback showing Elise noticing Josh's hands were different, and when she took the photo she saw the Old Woman that tried to possess him as a boy. Josh grabs Renai on the shoulder, saying "I'm Here" as she turns around and gasps in horror