Perhaps the most difficult title of the year to pronounce, Martha Marcy May Marlene (review) has made its way from Sundance to Cannes, around the world at different film festivals. Fox Searchlight will release it in October, but not before playing it at the New York Film Festival.

The film stars Elizabeth Olsen as Martha, a young woman who leaves a cult led by Patrick (John Hawkes). As her sister Lucy (Sarah Paulson) and her husband Ted (Hugh Dancy) take Martha in, they can’t cope with her disturbing behavior. Writer/director Sean Durkin explained how he determined what specific social interactions Martha would get just a little bit wrong.

One behavior audiences may not notice is that Martha doesn’t know how to eat socially. “For instance, one of the first things is when she’s eating, the first breakfast scene,” Durkin continued. “If you watch her, it’s sort of subtle, but she sort of doesn’t know how to eat. She’s sort of cautious to eat, she’s kind of playing with her food. Things like that, knowing at that point that she hasn’t eaten in front of a man in a long time without some sort of issue that was created by the separation of the eating meals at the cult. So it just grew out of things like that.”

Martha also goes skinny dipping and gets into bed with her sister and brother-in-law unannounced. That becomes creepy, because how do you explain to a full grown adult why that’s not okay? She should already know better.

“The swimming and getting into bed with them, it was just about redefining the rules there and having them carry over so she was stuck in a place where she didn’t know what not to do. Lizzie always sort of brings in what she brings in.”

As Martha flashes back to her time in the cult, audiences will pick up on where some of this learned behavior comes from. Durkin was careful never to spell it out though.

“That was really important to me, to not explain it but just to show it and have it gradually come out later,” Durkin said.

He also outlined the rules of the cult in his head, even if they don’t specifically make it onto the screen. “Oh yeah, definitely. I created the whole set of values and how they would operate and all that stuff.”

Durkin began the script for his first feature film by casually thinking about how he hadn’t seen a modern day cult movie before. Then he became more involved in research and developed a passion for the subject.

“For me, the most disturbing thing I found was the sexual initiation thing that seemed consistent. The stuff I read about and talked to people about was way worse than anything you can put in a movie because people just wouldn’t believe it. I had to tone it down a lot from things that I heard about.”

The film shows how Patrick abuses and manipulates young women. That was as far as Durkin felt comfortable exposing the real horrors of cult mentality. “Like really elaborate sexual rituals that were just so manipulative and abusive I don’t even want to say them out loud. I feel like in a film if things are too extreme, sometimes you lose your audience. It doesn’t matter if they know or not know. I just think you have to find an area, or I just wanted to find an area that’s a little more understandable.”

Durkin studied the research that was available on the famous cult groups. “I started by reading all of the big groups, like the famous groups of the ’60s and ’70s. Then I found some more local groups in upstate New York and Vermont and out west in the desert. Then I started watching some documentaries and then finding people who had been some of these more local groups.”

Real cult survivors became the most detailed source of research for Durkin. “My main source was three or four people, a couple of which had gone into these groups and left after a couple days because they were just passing by. That was really valuable to get an outsider’s perspective. The other thing was someone who had spent eight months in a group and escape.”

One might imagine it’s hard to put out a call saying, “I’m making a film about cults, I’d like to hear your story.” Durkin’s process was much more organic. Simply by starting the screenplay, he found vital sources of inspiration.

“It happens really naturally. When you’re writing, you just talk about it because that’s what you’re working on. People ended up coming to me because I would just be talking about it in general because it was what I was working on. Then someone would be like, ‘Oh, my sister, my brother or I was in a group.’ It was pretty common that people would come forward and want to share.”

Martha Marcy May Marlene opens Oct. 21 in limited release.