Carey Mulligan found herself propelled onto the world stage after she was nominated for an Oscar for her portrayal of the sharp, witty and painfully young Jenny Mellor in 2009s “An Education.” Though doors began to open for the actress, she was disappointed to discover that most of them led to rooms of similar shapes and sizes. “A lot of people just wanted me to sort of do what I had already done,” she recalls. “Films that reminded me of that part weren’t films that I was interested in.”

If there is such a thing as a safe and secure course in the development of an ingénue’s career anymore, then Mulligan has chosen not to follow that trajectory. The actress took one leading, and several supporting roles (the most high-profile of which was in Oliver Stone’s “Wall Street: Money Never Sleeps”) after “An Education” and then stopped working for a year.

When she returned it was in pursuit of projects that would move her beyond the limited scope of the classical leading lady and/or give her the opportunity to work with filmmakers that she found compelling. She began with director Nicolas Winding Refn’s urban fable/meditation on violence, “Drive.”

One of the most fascinating aspects of Mulligan’s character in “Drive” is that she is essentially a very traditional ingénue (beautiful, gentle, sweet, in emotional and physical danger) in a distinctly atypical setting. Mulligan herself, however, never envisioned Irene in quite that manner. “She was originally intended for a slightly older Latina, so I never sort of saw her as the girl, or the love interest in the film, even though she was,” she says. “That situation was a point where I hadn’t worked for awhile and I wanted to be in one of his films because I thought he made really cool films. He welcomed me into his house, and I lived with his wife and his kids, Ryan (Gosling) came round a lot and it just sort of felt like this strange commune.”

Mulligan’s next film, “Shame” (which will screen this evening as a part of the Los Angeles AFI Fest), offered the actress an opportunity to “lose herself” in a way she hadn’t done since her stage performance as Nina in Anton Chekhov’s “The Seagull.” The comparison between director Steve McQueen’s film and Checkhov’s play feels apropos in that both deal with the loss of (and aching longing for) innocence, and the characters’ fundamental inability to connect. Where “Drive” was a (metaphorical) step into a warm creative bath for the actress, “Shame” was akin to being tossed into an icy, murky, bottomless ocean. “When I read ‘Shame,’ it felt like Sissy was a character with no safety net,” Mulligan says. “And she was so far removed from anything that I had played before especially being on screen.”

For Mulligan, “Shame” was really difficult if ultimately rewarding, where “Drive” was “sort of just fun,” she says. “When I get a script, I can pick out the scenes that are going to be a hard day of work and I freak out, and I overanalyze them, and I worry about them for weeks and more often than not I’m sort of disappointed with what I do. With ‘Drive’ we were playing the fairytale side of the story. It was knight in shining armor, and girl stuck in a tower, and we had a pleasant experience. It wasn’t challenging in the way that ‘Shame’ was. It wasn’t pushing out of my boundaries; it was something that I was really comfortable in. And when I talked to Steve [about ‘Shame’], I talked a lot about how I felt passionately that I wanted to not do what I’d been doing.”

In McQueen’s film, Mulligan plays Sissy, sister to Michael Fassbender’s sexually addicted and emotionally calcified Brandon. Sissy makes an unannounced (and unwelcome) visit to her brother, which acts as a catalyst for a self-reckoning that he is neither willing nor prepared for. The siblings’ psychological development atrophied in their youth as a result of a trauma that is hinted at in the film but (rightfully) never fully explored. The purpose of the film is not to offer easily digestible answers but rather to pose textured and nuanced questions to an audience that likely has far more in common with the pair than they are comfortable confronting.

While Sissy and Brandon engage in behaviors that may seem to exist far outside the barriers of the “norm,” their motivations are all too relatable. Their individual responses to the abuse they experienced as children are almost archetypically male and female respectively.

“I think he’s decided to put himself in a very particular place” Mulligan says of Brandon. “He’s stuck in it, and he’s introverted, and he can’t become intimate with people. When he becomes intimate with people he shuts down. And I think she’s exactly the opposite. She just wants someone to save her. I think it’s not conscious, but I think that she’ll always be swept up in this dramatic cycle because she will give into any kind of experience and any kind of person she thinks might be the key to making her feel better. And it doesn’t work.”

As the title indicates, “Shame” deals with the most insidious of emotions. The shame that Sissy and Brandon experience is not born of a healthy conscious. It is a sickly residue of their youth. This shame, inherited from a poisonous family, acts as a malignant infestation. It creates addictions, compulsions, and desperate, unconscious pleas for release. Often, in women, it develops into a near constant need to apologize.

“My idea was that things were coming into her mind, constant reminders of what had gone on, images or ideas or words,” Mulligan says of her character. “And she finds ways to block them out. She’s loud, or she swears, and she provokes, and she keeps talking or she plays around with stepping forward on the subway track or she cuts herself. But definitely, she’s apologizing. She knows that her attempts to reconnect with her brother are misfiring and she can’t figure out why. She wants more than anything to find some peace with him.”

Though a shattered childhood will often bond siblings, it can also act as a wedge. The knowledge that the other is the only person who can truly comprehend the scale and manner of their internal damage attracts Sissy to the same degree that it repels Brandon. They are simultaneously each other’s dark mirror and magnet. “There is a disconnect between them,” Mulligan says. “Their shared history has put a distance between them, because they’re both so aware of what happened. And being called out on those things is very painful because when I attack him for the way he is sexually, or he attacks me for being promiscuous, we know where those things ultimately came from. And it’s so much more painful because it’s completely not discussed.”

Far from the light, communal experience that she enjoyed both on and off-set while filming “Drive,” Mulligan’s “Shame” co-star chose to maintain a divide that he believed would feed their work. “Michael and I kept quite separate from each other,” she says. “And we didn’t hang out outside of work. We didn’t talk that much apart from about the mechanics of the scenes. We just came in and did the work.”

Though she did participate in some cursory conversations with both Fassbender and McQueen about Brandon and Sissy’s background, none of the three felt that the particulars were key to the story they were telling.

Mulligan was drawn to the elements of McQueen’s approach when she saw “Hunger,” the film that brought both the director and his star Fassbender to the world’s attention. “There was honesty there,” she says. “Visually it was stunning but there was also a truth in the performances, a realness. I loved the way he filmed the actors. He seemed to give the actors a lot of space. I just loved the way he shot bodies, and faces, and eyes. There was purity to what he was doing.”

There is a common assumption that playing a character as raw and ravaged as Sissy would leave the actress damaged and depleted. For Mulligan, however, inhabiting Sissy meant a welcome opportunity to purge some universally relatable emotions.

“It’s strangely cathartic and I think that’s the thing I was kind of looking for that was similar to Nina,” she says, recalling Chekhov once more. “Because when it had gone well when I was working on ‘The Seagull,’ I would go home and feel really elated. The scenes I did with Michael were exhilarating and then we both felt kind of good afterwards. It’s great sometimes to get out that aggression.”

“Shame” was set in New York rather than London as McQueen and his writing partner Abi Morgan were unable to find anyone in Britain willing to openly discuss sexual addiction. It would appear that the citizens of the United States (and New York in particular) are far more forthcoming on the subject. The tales the scribes collected during the course of their research were so wrapped up in the culture of the city that they felt it necessary to locate the film there. As such, one might imagine that there is a more open dialogue on the nature of sex and intimacy in the U.S., and yet the irony is that our MPAA gave the film a restrictive NC-17 rating. Mulligan, like many, finds the rating both unsurprising and indicative of a bizarre moral ethos.

“I knew that Steve would never cut anything,” she says. “He was always uncompromising about what he wanted. So he was never going to cave in to a rating to make it more commercial. I do think it’s sort of an absurd contradiction with the amount of — I mean it’s such an obvious point — but the violence that we see in slasher films and horror films. That’s perfectly acceptable and then the naked body and sex is such a big deal. And the sex is not what it’s really about ultimately.”

Nor is the film truly about sexual addiction, which is merely a symptom of the true affliction: icy, unrelenting, unendurable alienation. Perhaps it is the subject matter that has frightened the MPAA. For “Shame” reveals no more or less (physically) than audiences were shown in the R rated “Forgetting Sarah Marshall.”

“Nudity was so prevalent in the 70s,” Mulligan says. “You know, so many of the teen movies will have so much sex and so many people walking around in bikinis and bare-breasted and that all seems to be okay. And then the minute you show it and its not funny, and it’s not sexy, and it’s actually unattractive, then it becomes a problem, which seems so odd.”

Far from a pretty picture, “Shame” paints a gruesome portrait of two human beings who are unwilling or unable to free themselves from the clinging shadows of internally and externally driven rage. Mulligan’s resolve to explore and expose a fractured inner life and to embrace a character that is both metaphorically and physiologically flawed is indicative of the path she has chosen for herself as an actress.

“In ‘An Education,’ I was just meant to be a 16-year-old girl,” she says. “I wasn’t meant to look in any kind of way. I just looked how I looked and I enjoy that. I feel a freedom in that. And I felt a great freedom in playing Sissy. I didn’t have to worry about what I ate, or how much I drank, and I didn’t have to work out. She was an alcoholic mess. She didn’t have any money to dye her hair. I mean I didn’t become an alcoholic, but I didn’t have to watch myself.

“It was so much more exciting to play that character that didn’t worry about her appearance in any way. I knew that when I stood up in that bath naked it wasn’t about whether I looked good naked or not. It was about who she was. And I knew that I was going to grow my hair out and have crazy roots and she wasn’t going to look good in any kind of way. I’m playing Daisy right now in the ‘The Great Gatsby’ and that’s very visual. She’s meant to look very well put together and pretty, but I would always like to lean towards character roles that aren’t based on appearance.”

“Shame” opens in select theatres on Friday, December 2.