First seen at Sundance last year, Martha Marcy May Marlene has been a talking point ever since for its unsettling look at a young woman haunted by her time as a member of a cult-like group.
The names of such 'cult' leaders as Charles Manson, Jim Jones and David Koresh conjure up some of the most dramatic news images of the 20th Century.
Yet new UK release Martha Marcy May Marlene may be one of the first dramatic features to explore what happens in this highly secretive world.
A young woman, Martha, makes a phone call to the older sister whom she has not seen for two years, asking to be picked up in the middle of rural New England.
The camera follows the next few weeks in her life, as Martha - played by 22-year-old Elizabeth Olsen - undergoes a crisis of identity.
She has escaped a cult-like farming community and is trapped by unsettling memories of her recent past.
She is consumed with fear, paranoia and guilt. She is also convinced that "they" are coming to reclaim her.
"I don't think much has been made on these groups before as it's very difficult to get anyone to talk about their experiences," explains writer-director Sean Durkin.
'Naturalistic'
"Yet the power these utopian-like cults exert [is] something that fascinates many of us."
Durkin was so interested in the subject he made a short film, Mary Last Seen, before embarking on Martha, his first feature.
"I wanted to avoid the cliches about religious groups, where everyone is brainwashed," he says.
"I feel these cults are often portrayed as an over-the-top caricature of themselves and I wanted to make something a little more naturalistic and subtle.
"I want the audience to understand their attraction, and why Martha gets involved in the first place."
During his extensive research, Durkin came across one particular true story that "just jumped out".
"It was the story of a young girl who had just left a cult that was just becoming more and more violent.
"I wondered how on earth anyone could settle back into normal society in the weeks following their departure."
Yet it was a personal friend who provided the film-maker with most of his insight into the story of Martha Marcy May Marlene.
"A friend confessed to me she had been involved in one of these groups and she very generously told me her story," he says.
"It had taken her years of therapy before she felt ready to share it."
Olsen - the younger sister of famous twins Mary-Kate and Ashley - had her own views on cults which changed during the making of the film.
'Terrifying'
"I have only now understood how someone might actually become involved in one of these groups," the actress says.
"I always thought of them as 'those crazy Manson people'. But this made me realise how easily it could happen.
"Martha is an intelligent young woman, and what is real and terrifying about the film is that it's not so outlandish."
According to Durkin, Martha Marcy May Marlene was conceived as "more of a psychological thriller".
"I wanted to make a more complicated scenario where Martha is struggling with the guilt she feels for her participation in this group."
The story of her experience is told in flashbacks that show how her initial acceptance into the sect is slowly mixed with sexual abuse and violence.
Patrick, the leader of the cult, is played by John Hawkes, who was nominated for an Oscar last year for his work in Winter's Bone.
"I wanted him to have charisma, to be charming, just like we know people like Koresh and Manson must have been initially," says Durkin.
"He has attractive qualities, such as idealism in the face of materialistic values, and even musical talent which gives him a lot of appeal."
"Patrick sings Martha a love song on his guitar and re-christens her 'Marcy May' and later 'Marlene'," continues Olsen.
"It's all so charming and plausible. If you were a teenage girl, wouldn't you fall under his spell?"
'Dislocated'
According to Olsen, organisations like the one featured in the film appeal to a need for community and belonging that many people crave.
"People don't get sucked into these groups because they look bad from the outset. There's always something good at the beginning that is being offered, like love, community and acceptance.
"Then the abuse starts. But if there are people around you telling you the abuse is okay, your view of what is normal and acceptable changes."
Martha Marcy May Marlene premiered at the Sundance Film Festival a year ago, where it picked up a directing prize.
Yet Olsen has also been singled out for praise for her performance and had been mooted as a potential Oscar nominee. She is still in the running for best actress at the Independent Spirit Awards in LA on 25 February.
"I hope I've done her justice," says the actress. "I know how dislocated Martha must have felt because after our weeks of filming the crew had become a family to me.
"Then I was required to do my first really emotional scene, at a big party. Basically, it's one long shot of me having a nervous breakdown.
"They had hired in a lot of extras for that day and I found it really hard to function outside the security of my new 'family'."
Martha Marcy May Marlene is out in the UK on 3 February.
