We open with some footage shot on Super 8 film. We see four people with bags over their head and nooses around their necks - a father, mother, and two children. The nooses are draped over one branch and tied to another branch that is being sawed through from above by an unseen figure. The branch eventually snaps and as it falls the family is raised into the air, where they hang and die. The title card appears on the bottom of the screen.
We cut ahead to the future to see a new family moving into a house. Two deputies watch the movers from across the street, as the Sheriff (former Presidential candidate Fred Dalton Thompson) pulls up. The sheriff gets out and criticizes the deputies for not talking to the new family. The sheriff heads over where he is greeted by Ellison (Ethan Hawke), the head of the household. It turns out that Ellison is a non-fiction crime writer who moves from town to town investigating gory, unsolved murder cases. Ellison asks the Sheriff if he wants a signed copy of his first and only successful book, Kentucky Blood. While the Sheriff praises his work in that book, he says that Ellison's work in his much less-popular follow-up books was shoddy at best. He tells Ellison the law department did a thorough investigation of this murder (the family hanging from the tree) and warns Ellison to leave town. Ellison refuses, and the Sheriff tells him that he thinks this move is sick, since Ellison is moving his family into the very house the murders took place in.
After the Sheriff leaves, Ellison goes inside. His wife, Tracy (Juliet Rylance), asks if this will be their last move. He promises it will, and it also becomes clear that Tracy has no idea either what murders he is investigating, or that they have moved into the house the murders took place. Ellison walks into his daughter Ashley's (Clare Foley's) room where she is painting on the walls. She says she hates having left their old town, and Ellison promises that if his research here is unsuccessful, they will move back to their original home. He also tells her that the house rule is that she can paint on all her walls, but nowhere else in the house. Ellison then carries a box into the attic and sees a scorpion - dropping the box on the scorpion to kill it. He looks up and sees another box in the attic and sees it is filled with home video shot on 8 MM film and a projector. The films are listed Hanging Out, Sleepy Time, BBQ, Lawn Work, and Pool Party, with two bearing dates.
Later at dinner, we learn that the family is struggling financially. Not only were his last few books (and a foray into fiction) unsuccessful, but they are unable to sell the house they just left due to the bad housing market. Ellison is sure, however, that this murder he is researching now will lead to a book even bigger than Kentucky Blood, and the family will reap the rewards that come with it. At the insistence of Tracy, Ellison reminds Ashley and his son Trevor (Michael Hall D'Addario) of the rules that they must not go in his study (so that way they won't be exposed to his gory research) and that he will leave his study locked. Both kids say they would rather go home than live here. As the family gets ready for bed, Ellison decides to start setting up his study right away.
He puts up his corkboard, starts his computer, and takes out his notepad. We discover that there was a third child in the family that was hung from the tree, and that she disappeared the night of her family's murder. He then decides to watch the first of five films in the Super 8 collection. The video "Hanging Out." It shows the family that was hung enjoying playing in the backyard under the tree. Then, the video immediately cuts to showing the family being hung. He then loads the next film, "BBQ," dated a few years prior. We see another, different family, having fun camping in the woods and unloading their equipment from their station wagon. The film then cuts to show three-fourths of the family chained into the station wagon in the garage before the car is lit on fire and consumes them. Ellison puts in the third film, "Pool Party," and it is of a third family playing in a pool. It then cuts to most of the family duct taped to beach recliners and then dragged into the pool where they drown. Ellison takes a shot of whiskey, and hears a noise. He investigates and finds his daughter wandering around unable to find the bathroom in their new house.
The next morning, Tracy takes the kids to school, and Ellison continues his research. He pops in a fourth film, "Sleepy Time," and it shows someone skulking through a home's hallways at night. The unseen videographer opens the doors to show two adults sleeping. The videographer walks up to them and slits their throats with a knife. The videographer then goes into a young boy's room and slits his throat, as well. Ellison is able to pause the video and sees a personal item labeled with the family's last name and the city St. Louis. He does some Internet research and discovers the whole family was killed, except for one child who went missing. He also determines that the family who were hung lived in the house where the people whose throats were slit lived before they moved to the house where they died. Tracy comes home with Trevor, saying that he got in trouble in school because he drew a picture of four people hanging from a tree on his classroom's whiteboard. Trevor has clearly found out about the murders his dad is investigating. Later that night, he and Tracy fight about his work, but she says she will stay by him for this last book.
That night, Ellison re-watches the tapes. In the one where the family is drowned, he catches a glimpse of a figure with a white, triangular face and black eyes. He pauses it to get a closer look, but then the film starts to burn. He is only left with a frame of the mystery man (likely the videographer/killer) in profile. He then hears a bunch of noises and goes out to investigate. He sees movement in one of their moving boxes, and as he walks closer, the top opens and his son unfolds from within, screaming at the top of his lungs. Ellison grabs him and wakes him up as Tracy runs out of the bedroom. Trevor has had a night terror, something he has suffered from but not in many years. Nonetheless, the family laughs it off, saying it isn't the weirdest place they have found him.
Later on, Ellison cuts all the films together and then records them on his digital camera and downloads them to his computer. He then finds the mysterious man's visage in all of the films, caught on tape somewhere in the background. He prints out screen shots of each place where the face is seen. Ellison also finds a strange symbol in all the films. He can't bring himself to watch the final film yet. As night falls, the power goes out, and he hears noises from the attic, though the attic door is closed. He goes into the attic and sees something rustling under a board. He flips the board over to find a snake that slithers off. On the other side of the board he finds a collection of children's drawings, each listing the first names of the family members who died in the videos he has seen. Also, in each drawing is a figure labeled Mr. Boogie. He hears more rustling and tries to get back to the attic entryway but the floor gives way and he falls to the level below, injuring his leg.
Tracy calls the police and they patch up his leg and theorize he had heard squirrels. One of the deputies (James Ransone) stays after the rest leave and asks for a signed copy of Kentucky Blood and offers to help Ellison with research if he can get credit in the new book. Ellison asks him to research the family who was burned alive, giving him the details of the case and the year it occurred. Ellison then pops in a VHS copy of an old interview he did when Kentucky Blood came out. In the interview, he says he puts family first and that he writes to give the dead justice rather than to bring himself fame and fortune. He takes the tape out and puts it in a drawer with dozens of other old interview tapes, suggesting his stated motives are disingenuous.
Later that night, he hears a noise from his study. He walks in and sees the projector playing the films, the films running on his laptop, and a light over the stills he has printed out. He sees the still printed from the deaths of the family who lived in his house, and notices the face of Mr. Boogie hiding in the bushes in the still. He shuts off the videos and holds the picture to the window to compare it to the actual landscape. When he takes down the picture, he sees a face in the same place that Mr. Boogie's was in the picture. He leaps back in fear, grabs his bat, and runs outside. There, he finds Trevor in the bushes, shaking from night terrors. He drops his bat and helps Trevor inside. Ellison returns for his bat and is menaced by a dog, while unbeknownst to him, five spectral children lurk behind him.
The next morning, the deputy calls while Ellison is looking at the pictures of Mr. Boogie on his laptop, and reveals the identity of the burned family. He confirms that one child was abducted from that home. While the conversation is occurring, Mr. Boogie's image on the computer turns its head, staring out at Ellison. Tracy teaches Ashley how to make Ellison's coffee just the way he likes it, though Ellison largely ignores her when she brings it to him. The deputy swings by some time later with the files from the two other murders. The deputy displays he is more clever than Ellison thought by linking the slayings together as a pattern. Ellison finally confides in him, showing him the pictures of Mr. Boogie and the mysterious symbols. The deputy puts him in touch with a professor of occult crimes (cameo by Vincent D'Onofrio) who informs him that the figure is Bughuul (Nicholas King), an ancient demon, and the symbol is his calling card. Legend has it that Bughuul collects the souls of children and feeds on them over time, while causing death of the child's family.
That night, Ellison once again hears sounds throughout the house. He grabs his baseball bat and enters his locked study, again finding his projector playing, though he had taken it down earlier. He sees a new video on his computer, this one showing him in distress with spectral fingers reaching out for him. He searches his whole house, unable to see the spectral children that are following him. He checks his kids' rooms to make sure they are asleep. Though Ashley appears asleep, she is actually awake and watching one of the ghostly children painting a picture of the hanging family and Bughuul on her wall. Ellison eventually falls asleep on the couch.
The next morning, he calls the deputy and asks if the deputy thinks he is crazy. Though the deputy notes that Ellison is a heavy drinker, he says he doesn't think he is crazy. The deputy does say that Ellison should give up his research. That afternoon, Tracy and Ellison find out that Ashley has broken the rules, and has painted outside of her room. The picture is of a young girl. While being lectured by her parents, Ashley says the picture is of the girl who lived there before them, and that this location was the girl's room. This leads Tracy to discover that this is the house where the hanging murders took place. She and Ellison fight, with Ellison saying that writing is his legacy. Tracy disagrees, saying that she is his present and his children are his future. He storms out and retreats to his study. He finally plays the fifth and final video entitled "Lawn Work." On it, we see a lawnmower being pushed along over a lawn at night. Suddenly, a series of people are revealed on the ground and the lawnmower runs over them, slaughtering the family. This video confirms that Bughuul has murdered all these families and abducted one child each. That night, he is awakened again by noises throughout the house. He searches up to the attic and finds the five spectral children watching the videos, this time visible to him. Bugghul then attacks Ellison, and he falls down the attic steps. Ellison contacts the professor who has done further research. The professor says a scorpion, snake, and dog are the precursors to Bugghul's arrival. He says that Bugghul is able to cross into this world through depictions of his images, and can often possess people who see his image before abducting them into his alternate universe.
Ellison, realizing the danger his family has been placed in, takes the videos and projector, and burns them. He wakes Tracy and the children and load them into the car to return to their still unsold original home. On the way out of the town, the Sheriff pulls them over and asks what Ellison will write in his book. Ellison says he will likely write nothing at all, before speeding off into the night. When they arrive at their former house, he deletes all evidence of Bugghul from his computer. He believes that destroying all images of Bugghul will stop him from crossing over and harming his family.
All the family seem happy to be home. The deputy continues to call Ellison, but he ignores all the calls. Later that night, Ellison hears some noises. He goes into the attic and finds the box of 8 MM film, projector, and an envelope with additional films entitled "extended ending shots." Ellison can't help himself, and plays the new footage in his study. In each one, it shows that the missing children were the ones who killed their respective families before making a quiet sign by holding their finger to their mouth and then disappearing. He gets another call from the deputy and, this time, answers the phone. The deputy says that the problem is that Ellison has moved. The deputy says he did further research and discovered the link between all the families. Each family had moved into the house of the one slaughtered before them, and then when they moved after that, they too were slaughtered (i.e. the family who was hung lived in the house where the family had their throats slit - ostensibly being exposed to Bagghul there - and once they moved to the house where Ellison and family were, Bagghul possessed their daughter and killed them via hanging). By leaving the house where the family had been hung, he played right into Bugghul's hands.
Ellison then hangs up the phone in shock, but before he can react he starts swaying. He looks down at his coffee mug and sees a note from Ashley, who had made (and drugged) his coffee.
When Ellison awakens, he is duct taped. Ashley walks in, dragging an axe and a camcorder. She tells Ellison that she will make sure he will be famous again, more famous than ever. She raises the axe and brings it down, then walks to her mother's and brother's respective rooms to kill them, as well. She then adds their names and images to the board that the other children had drawn their family's deaths onto that Ellison had found earlier in the film. She walks through the hallways and, free of all rooms, has painted pictures in blood (including Bugghul's symbol). Ashley plays the video on the projector, and the five ghostly kids walk towards her making the quiet sign, a sign that she reciprocates. Bugghul appears behind her, takes hold of her, and they jump into the video footage.
The last scene shows the videos in the attic, with a sixth one now added entitled "House Painting '12." The box awaits the family that will move into Ellison's house. Then, Bugghul jumps out at the audience, hoping to elicit one final scream from the viewer.
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