Director Scott Derrickson describes his film, Deliver Us from Evil, as " Serpico meets The Exorcist".
A good old-fashioned movie that combines violent crime and supernatural horror, it is based on Beware the Night, a 2001 book by former New York policeman Ralph Sarchie and journalist Lisa Collier Cool that tells how the 26-year NYPD veteran was pulled into the bizarre world of demonic possession and exorcism.
This cinematic retelling is expectedly gritty: it is set in South Bronx, New York, which - back when Sarchie was patrolling the streets - was one of the most dangerous boroughs in the entire United States. As befits reality, its protagonist is a tough nut too.
"The real Ralph Sarchie is an extremely fascinating guy," says Derrickson of the cop turned demonologist. "He is foul-mouthed, hardcore, volatile. He's a lapsed Catholic who ends up being an assistant to an exorcist."
The dramatic potential of Sarchie's story was a major draw for Derrickson, no stranger to horror films: he co-wrote and directed The Exorcism of Emily Rose in 2005, as well as 2012's Sinister. Still, Deliver Us from Evil is not a straightforward adaptation of Sarchie's tale.
Rather, the film - which is co-scripted by the 37-year-old Derrickson and his regular screenwriting partner Paul Harris Boardman - is a composite of various incidences and exorcisms detailed in Sarchie and Collier Cool's book, with some creative licence having been taken with Sarchie's character as well.
"While we were creating our own version, there was a lot about the real Ralph that we selfishly stole, and some bits that I selfishly left behind," says Eric Bana, who plays Sarchie.
"Really at the end of the day, the story you're trying to tell becomes the boss. You are trying to serve the audience by picking and choosing what you think is going to make the character the most interesting."
While filming Deliver Us from Evil, Bana was faced with the additional pressure of playing a real-life person who made regular visits to the set, after Derrickson invited Sarchie to attend the shoots. But the actor was unfazed by this experience.
"I'd like to think that I'm at the point in my career when I'm experienced enough to be able to let go of that stuff," the 45-year-old Australian says of the potential for self-consciousness when the person you're playing is looking on. "If I thought it was going to affect my performance, I would have said something."
Bana is also not one to let horror films affect him negatively. This genre is an interestingly divisive category: people either flock to horror films, or steer well clear. Bana views them as possessing elements that "people can connect to".
"We might go and see a movie and while it's escapism, we can't necessarily relate to it," he says. "But we can all relate to being scared. It's a primal feeling in the same way that people enjoy watching a love story where you end up crying. The two are kind of similar in a sense, because they tap into every primal response that we have. There's a bit of adrenaline in there too."
Also on board the Jerry Bruckheimer-produced project is 37-year-old Venezuelan Edgar Ramirez. A multi-lingual, well-travelled actor widely considered one to watch after his turn in Zero Dark Thirty, he brings an intellectual gravitas to his role as Mendoza, a Catholic priest who convinces Sarchie to work on a case he believes involves paranormal forces - specifically, a murderous soldier possessed by demons.
"To me, this is a movie about forgiveness and compassion and the power of forgiveness in our daily lives," Ramirez says. "In the end, whether you believe in demonic possession or not, there is an ongoing battle between goodness and evil that transcends religious beliefs. It is something that is inherent in the human condition."
Ramirez says he wanted to find the heart of Deliver Us from Evil, and believes he has succeeded. "For me, it was to be aware of the fact that there are demons and forces inside all of us that try constantly to keep us away from our centre, from the peace that is inherent to all of us. That is the subject of this movie, and it made me feel more comfortable in dealing with those subjects."
To prepare for the part he watched videos of exorcisms, and interviewed exorcists, and claims that what he saw convinced him that whatever was happening wasn't play-acting.
"I was never sceptical. That is not the way I look at the world. I try to stay open-minded," the Catholic-raised actor says.
"What I got from the interviews with exorcists was the immense amount of care for others. It is the ultimate form of compassion to work next to someone through such an extreme process of suffering. I saw real exorcisms on tapes. There was one where a person blinked three times - and never blinked again for more than 30 minutes.
"That was way more frightening than any screaming or hysterical reaction, because the level of solitude and isolation that I felt in that person was devastating."
Derrickson says he was hoping to mine just that sort of terror through this film. "There is a lot more mystery to the world than we can explain. Mystery and mysticism keep us sane and alive. I like to release the emotion of fear, and movies like this force us to confront these fears. It's better to wrestle with it until it loses its grip on you."
Deliver Us from Evil opens on Thursday