While WonderCon was noticeably short on horror offerings this weekend, the convention did feature a lively panel on Saturday for director Scott Derrickson’s follow up to Sinister, the exorcism film Deliver Us from Evil (watch the trailer here), hosted by our own Chris Hardwick. The film is described as a supernatural thriller that follows a detective who begins investigating a series of disturbing and inexplicable crimes and joins forces with an unconventional priest (Edgar Ramírez) schooled in the rituals of exorcism to combat the frightening and demonic possessions that are terrorizing their city.

The panel kicked off by showing off a five minute clip, which consisted of the trailer peppered with interviews from the real Ralph Sarchie and a few additional bits from the film. Derrickson was joined by cast members Eric Bana, Edgar Ramirez, Olivia Munn, and Joel McHale as well as mega-producer Jerry Bruckheimer.

Bruckheimer revealed that the feature, based on Ralph Sarchie’s book “Beware the Night,” had been in the works for about ten years. Derrickson had actually started writing on the project around its inception, but left to work on other things and eventually came back to make the movie.

Hardwick began by asking star Eric Bana how one approaches being involved in a horror film, especially one dealing with possession. Bana replied, “I was coming from a skeptical place… This guy [Scott Derrickson] scared the bejeezus out of me in pre-production. He had access to some materials, along with Ralph Sarchi, the real guy, that they shared with me that I really wish I hadn’t seen and clearly had a week of a half of not being able to sleep correctly.” On the issue of being a “believer,” Bana continued, “I just realized, learning a lot from Scott and Ralph, there are varying shades of grey. It’s not as simple as ‘Someone’s not possessed’ and ‘Someone’s fully possessed.’ There’s a million steps in between.”

The uncertainty of the actors own personal beliefs regarding the subject matter was echoed by Edgar Ramírez, who plays a priest in the film, a character who is a combination of two real life people. Ramírez told WonderCon, “I watched, by accident, The Exorcist when I was six years old. It was an accident because I couldn’t sleep alone or with my lights on for the following two years. So half waythrough the process because of this movie, I was wondering, ‘Why did I take on this movie?,’ because my lights were on again and they were on for the three months of preparation through the shoot…. I walked into it with an open mind. I cannot confirm or deny the existence of something that I don’t fully understand.”

Olivia Munn, who had some delightfully inappropriate banter with Hardwick throughout the panel, echoed the sentiment of her co-stars. “To me it got serious when Eric told me that he had seen the actual exorcism from the – the NYPD has this footage from their exorcisms and he couldn’t sleep for three weeks and he wasn’t a believer, but you couldn’t sleep for three weeks? OK, big Australian man… So then I asked to see them. I have to see them, and then he [Eric] heard I had asked to see them and Scott was going to let me see them and Eric said, ‘I heard that Olivia asked to see them, you cannot see these. You won’t sleep.’ And that’s when it got really real for me and I said, ‘If I can’t see them, then I have to see them,’ and I watched them and he was right. I watched half of one and I cried and then I kept the lights on and then they’re still on.”

Community star Joel McHale plays Bana’s partner in the film. A longtime friend of director Derrickson, McHale explained how he came to be involved in the project. “I allowed Scott to put me in this movie… I am very good friends with Scott and he took pity on me and wrote this role with me in mind,” McHale told the audience. “I remember him telling me about Ralph Sarchie riding around with him and all of a sudden [the movie] became a real thing, and then Jerry allowed me to be in the movie as well.”

Derrickson summed up his interest in a project like this: “I like zombie movies where the audience knows there aren’t really zombies or vampire movies there’s no real vampires, werewolves. Exorcisms are a fact, they really happen, and the footage that I showed Eric and Olivia is so disturbing because it’s real. Real footage that happened to real people, and I like two things about that: I like that it allows a different kind of fear to enter the audience if you do it properly, because it’s a fear that I think goes deeper than other kinds of genre films, but I also like that it opens the mind to the mysteries of life. And I’m a big believer that horror films are meant to be fun and they’re meant to be a form of escape, as all good entertainment is. But at the same time, they awaken good things in us when they’re good movies and a good horror film, and certainly a good exorcism movie, makes you think that the world is a bit more magical and mysterious than what you’re often told by the powers of the world that we’ve got everything figured out, and I don’t think that’s true, and I like movies that remind me that’s not true.”

Deliver Us from Evil, written and directed by Scott Derrickson and starring Eric Bana, Olivia Munn, Edgar Ramírez, Sean Harris and Joel McHale, opens in theaters July 2.