Sinister (2012)

Struggling true crime writer Ellison Oswalt fails to replicate the success of his debut book, made famous for helping solve a crime. He and his family move to a home in Chatsford, Pennsylvania, which, unbeknownst to his wife Tracy, is the site where the Stevenson family were killed via hanging. Hoping to revitalize his career, Ellison intends to research the Stevensons' murders and the subsequent disappearance of their youngest child, Stephanie.

In the attic, Ellison finds a box containing a scorpion, a projector, and film reels labeled as home movies. The footage displays families being murdered in various ways, such as drowning and immolation, seemingly perpetrated by the cameraman. Ellison contemplates giving the videos to the police, but ultimately decides to keep them. He notices a cultic symbol and a strange figure in the film, matching one reel to the murder of the Miller family in 1998 and the disappearance of their 13-year-old son Christopher.

While investigating noises in the attic, Ellison finds a king snake and childlike doodles of the killings, which feature a figure called "Mr. Boogie". He falls through the ceiling; emergency services are called, including a deputy who enthusiastically agrees to help Ellison, jokingly accepting the nickname "Deputy So-and-So". Ellison later encounters a Rottweiler in the garden, which flees. So-and-So informs Ellison that the murders took place in different cities at different times, with a child from each family having disappeared. Additionally, he learns that the Stevensons lived in the Millers' former house. Ellison consults occult specialist Professor Jonas about the symbol in the films, which Jonas links to Babylonian god Bughuul, who lures children into his realm and consumes their souls. Jonas suspects the murders are part of a cult initiation rite rather than the work of a single murderer.

Ellison's children, Trevor and Ashley, exhibit erratic behavior as ghost children begin haunting the home, including Ashley painting Stephanie on the walls. Tracy is furious that Ellison moved them into the site of a crime without her knowledge. One night, Bughuul appears to Ellison while he's watching the films. Ellison destroys the camera, projector, and reels, and moves the family back to their old home. Jonas sends Ellison images associated with Bughuul, including the mysterious symbol and a scorpion, snake, and dog. Jonas tells Ellison that early Christians believed Bughuul was summoned through artwork of him, and that he possessed children who see them. Ellison finds the undamaged projector and reels along with a new reel labeled "Extended Cut Endings".

So-and-So tips Ellison to the pattern of families being killed after moving in and fleeing from the previous victims' house. Ellison watches the new footage, which depicts the missing children entering the frame after each murder, revealing that they committed familicide under Bughuul's influence. Ellison passes out, as his coffee was spiked by Ashley. He, Tracy, and Trevor awaken bound and gagged. Ashley states that she will make Ellison famous again before dismembering them with an axe, using their blood to paint Bughuul's face on the walls. She doodles their corpses on the lid of the film reel box as footage of her murders plays on the projector. Bughuul appears and consumes Ashley's soul.