| Director | Oren Peli |
|---|---|
| Genre | found footage, horror film, thriller film |
| Runtime | 87 min |
| Country | United States |
| Budget | $15,000 |
| Box office | $194.2 million |
Katie drives up to a house in San Diego as her boyfriend and housemate Micah records her from the driveway using his new video camera. Katie claims that an evil presence has been haunting her since she was a child and suspects it may be responsible for strange happenings in their home, so Micah sets up the camera in their bedroom to record any paranormal activity that occurs while they sleep. Psychic Dr. Fredrichs visits the couple at Katie's request and after a conversation suggests that she is being haunted by a demon that feeds off of negative energy and is intent on tormenting her. He advises them not to communicate with the demon and recommends they contact a demonologist to handle matters, but Micah is dismissive of this advice and continues to film and provoke the presence over the next few weeks.
The camera captures many strange occurrences at night: minor noises, flickering lights, and door movements, soon escalating into loud thuds, violent door slamming, and demonic grunts and screeches. One night, Katie gets out of bed appearing to be in a trance, stands beside the bed staring at Micah for two hours, and then goes outdoors where Micah later finds her, none of which she recalls the next day.
Katie is increasingly irritated by Micah's flippant and dismissive behavior about the strange activity. Micah brings home a Ouija board against Katie's wishes. When the couple leaves the house for a night out, the camera records the board's planchette moving by itself before the board spontaneously catches fire. Katie pleads with Micah to contact a demonologist but he refuses and continues his efforts to document events. The couple wakes one night to find non-human footsteps on baby powder Micah sprinkled in the hallway; they lead to an open attic hatch. Micah discovers a burnt photograph in the attic which features a young Katie, though the photo was thought to have been destroyed in a house fire over a decade prior. After Katie finally reaches out to the demonologist and learns he is out of the country, psychic Dr. Fredrichs returns but is alarmed by the energy of the home and flees. The next night, Katie is pulled out of bed and tormented by an unseen force. The next morning, Micah photographs a bite mark on Katie's back, motivating him to prepare to get them out of the house, but Katie, now showing signs of a possession, abruptly changes her mind and insists that they stay.
On Night #21, Katie gets out of bed again in a trance and stares at Micah for hours before going downstairs. Shortly thereafter, she screams for Micah, who frantically rushes to help her. Loud thuds are heard downstairs and Micah screams in pain. A few minutes later, Micah's body is hurled at the camera and Katie is revealed standing in the doorway with blood on her shirt. She crawls to Micah's body and sniffs it, then looks up at the camera with a grin, lunging at the camera with a demonic snarl on her face before the scene cuts to black. The epilogue text states that Micah's body was discovered by the police days later, and Katie whereabouts are unknown.
Once DreamWorks/Paramount acquired the film, the original ending was shown at only one public viewing before being scrapped; two new endings were developed, one theatrically released above and the other available as an alternate ending on home releases.
Katie returns to the bedroom alone, covered in blood and holding a large kitchen knife. She sits on the floor against the bed and rocks back and forth. The next day, a friend of hers leaves a concerned message at 2pm. At 9pm, she visits the house; meanwhile, Katie stops moving. When her friend discovers Micah's body downstairs and runs away in panic, Katie resumes rocking back and forth. Thirty minutes later, two police officers enter the house and reach the bedroom where they find the possessed Katie with the knife. She stands up, returns to her normal state and asks for Micah. After the attic door slams by itself, one of the officers panics and shoots and kills Katie. The camera fades to black as the police officers continue searching for the source of the slamming sound. An epilogue text appears, dedicating the film to the memory of Micah and Katie.
This ending was exclusively shown at the 2007 Screamfest Film Festival and was never released officially by Paramount or Blumhouse in any capacity, save for the documentary Unknown Dimension: The Story of Paranormal Activity (2021) in which a snippet of the ending was presented. Second Sight Films released a special edition Blu-ray of the film for the UK under license from its regional distributor Icon Productions, and included the full original ending as a special feature. The original cut of the film (dubbed the "Festival Cut") would later leak on various forums.
After killing Micah off-screen, Katie comes back upstairs alone holding a knife on her hand. She closes and locks the bedroom door, approaches the camera, and after smiling, she slits her throat before collapsing dead. The scene then fades to black.