A documentary crew stumbling upon more than they bargained for is nothing new in horror films, but "The Last Exorcism" plans to deliver a shockingly demonic twist to the formula.

Opening in theaters Aug. 27, the film was directed by Daniel Stamm ("A Necessary Death"), based on a script by "Mail Order Wife" writing duo Huck Botko and Andrew Gurland.

"The Last Exorcism" recently premiered at the Los Angeles Film Festival and Comic-Con International. It stars Patrick Fabian ("Big Love," "Veronica Mars") as the Rev. Cotton Marcus, who brings a documentary crew to chronicle his final exorcism on a remote Louisiana farm.

Producers Eric Newman ("Children of Men") and Eli Roth ("Hostel") joined Stamm at the Comic-Con premiere.

"This is not like a studio movie," Roth told the audience after the screening. "This is not a manufactured movie. This is not a remake. This is not a sequel. This is a purely original independent film that was just made with spit and glue, and love for the genre."

Presented entirely in a documentary format, "The Last Exorcism" required a director with a special eye for authenticity, Newman said.

"We had seen this unbelievable movie 'Necessary Death,' and we thought 'this guy [Stamm] is perfect,'" Newman explained. "And he came in and wanted to put his own stamp on the movie. And we really feel like he did. It's very much his film. : He did an unbelievable job."

The documentary format seemed like a perfect fit for the film, according to Roth. It also helped to distance it from William Friedkin's "The Exorcist."

"I love first person horror," Roth said. "I think that when it is done well, you get 'Cloverfield,' you get '[Rec].' They can be really, really scary, and you really get the feeling that you were there in the room."

Many of the scares of "The Last Exorcism" are reinforced by a commitment to presenting a meaningful picture of its characters, according to Roth. For instance, the script allows ample time for the audience to become familiar with Marcus before he is thrown into the horrors of his final exorcism.

"It's very much about the characters," Stamm said. "And just about the implication of horror rather than the spectacle itself."

Grounding the film's horror with a strong sense of reality, not the fanciful, was another key concern for the filmmakers. That goal largely hinged on Ashley Bell, who plays the girl suffering from the possible possession, and who could perform her demonic stunts without the aid of special effects.

"If it was something that a person couldn't do, we were not going to do it," Newman explained. "That was the beauty of Ashley's ability to contort like that, which seems like it is otherworldly, but she actually did it."

As a result, the film carries a level of ambiguity that should keep audiences guessing, Roth said.

"What I loved about this story is that I thought it did a great job of presenting both sides very equally; to me what is interesting is the clash of science and religion," he explained. "But I think it is a very, very interesting idea of don't mess with forces that are beyond your understanding and your power."

One force Roth is hoping to harness is the enthusiasm of fright fans. He anticipates that they will embrace "The Last Exorcism," and consequently he is seeking their help.

"In order for movies like this to survive it's 100 percent in the hands of the fans," Roth said. "Please, if you love the movie, and you can take that 30 seconds to type a sentence on Twitter, that is what is going to give this film life."

See our review of the film here.

"The Last Exorcism" also stars Iris Bahr, Louis Herthum and Caleb Landry Jones.