The cross pitch for The Last Exorcism must have gone something like this: The Exorcist meets Rosemary's Baby in the style of, what the hell, This Is Spinal Tap. (Insert record scratch sound here.) How writers Huck Botko and Andrew Gurland managed to get a feature film deal rather than a tongue-lashing by development executives is likely the result of a trend that's risen in the industry of late: the mixing of two genres into a profitable subgenre, the horror mockumentary.

The mockumentary form—that is, a narrative film in the trappings of a nonfictional documentary—traces its roots to the "Swiss Spaghetti Harvest," an April Fool's Day hoax perpetrated by BBC news producers in 1957, which depicted pasta farmers plucking spaghetti noodles from trees. Later, Christopher Guest and company would perfect the genre, most famously with the Rob Reiner–directed mock-rockumentary This Is Spinal Tap, followed by the Guest-directed Waiting for Guffman, Best in Show and A Mighty Wind.

Meanwhile, television hybridized the genre with reality shows and birthed franchises such as The Office and newer iterations like Parks and Rec. Clearly, the mock-genre works for comedy, but does it work for horror?

Yes. The forerunner to the recent spate of horror mock-docs is, of course, 1999's Blair Witch Project, which elevated shaky, camcorder cinematography to an art, or at least an acceptable idiom, and proved that fake horror flicks can be real earners. To date, the indie flick has made $240 million—4,000 times its $60,000 budget. It also spawned a franchise of less successful sequels as well as innumerable knock-offs and parodies such as the Tony Blair Witch Project and The Blair Witch Project with Linda Blair, the star of the proto-exorcism film The Exorcist.

A more recent winner in the subgenre, Paranormal Activity, improved the earnings ratio. Released last year, the film has earned $108 million thus far, which is nearly 10,000 times its budget of $11,000. Of course, high box office receipts doesn't necessarily equate into high art; however, it does account for the slew of mock-horror-docs coming to a multiplex near you, including The Last Exorcism, in which a charlatan exorcist attempts personal redemption by ridding a Southern school girl of a demon named Abalam.

"I was so surprised when I saw The Last Exorcism, because I've been watching horror films all my life," says the film's star, Ashley Bell, 24, who plays 16-year-old Nell, a Louisiana girl who may or may not be possessed. She first saw her film's antecedent, The Exorcist, when she was 10; at director Daniel Stamm's behest, she watched its less popular sequels and then heeded his instruction: "Don't do that."

"Daniel would hint as to where to look at the camera and for how long, what to tell, what to lie about, what not to tell," says Bell, whose performance as a wide-eyed innocent is the film's greatest asset. "The camera was really another character, and it was fun to kind of use it to manipulate the audience and play with it and against it."

Bell's sensitivity to the form added to her character's on-camera verisimilitude. When "Nell" appears nervous during an on-camera interview, she easily endears herself to the audience, which makes it all the more creepy when she's in a satanic trance.

"As you're watching it, it's as if you're in a 360 degree arena and don't know where the next attack is going to come from," Bell observes. "You always feel so vulnerable and so exposed, and I really like that."

Audiences apparently like it, too. The film, which offers little in the way of special effects, rudimentary costumes and only a handful of locations occupied by relatively new (read: cheap) faces onscreen, has made its $1.8 million budget back ten times over, earning $20 million in its first week of release. Though some critics have grumbled that the film isn't scary enough, it's likely scaring the shit out of Hollywood, which is used to padding salaries with outsized film budgets. Mock-doc or not, no one can mock the math, which will likely lead to the rolling of executive heads. For Hollywood, the real horror show is just beginning.

Producer Daedalus Howell makes media at DHowell.com.

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