She’s different from her older sisters, those lovely, startled, woodland creatures with extraterrestrial eyes and Miss Havisham hand-me-downs and Christmas cards from Uncle Jesse and Joey. She’s taller, maybe? Equally beautiful, more solid, less familiar, with velveteen skin that appears to completely lack pores.

Here is a woman who could pick up her cellphone and get Mary-Kate or Ashley on the line just like that, who could ask them sisterly things, like what was the name of that lotion again, or who remembered the card for Mom’s birthday, or was it semi-sweet chocolate chips or regular? Mary-Kate, hello?

It becomes clear that Elizabeth Olsen will graciously answer questions about what it was like — What was it liiiiike? — to grow up around The Twins, or how she feels — How do you feeeel? — about suddenly being on the verge of fame. “I never wanted to feel like I was using anyone,” she says in her throaty, old-soul voice. “I always knew that I would have a different experience than my sisters.”

But such questions feel tawdry in the presence of Elizabeth. Elizabeth seems better than these questions. Seems . . . too poised? Too unflappable?

Elizabeth Olsen is about to be all over your cineplex, and Fandango and the entertainment magazines, but right now she is still pre-Hollywood, pre-paparazzi, pre-It, untouched in a way that makes you want to say, “Let’s get out of here, Lizzie,” and then take her on one of those girlie road trips that always seem to be soundtracked by the Cranberries. This is her Before picture.

* * *

The movie is very good.

There are three movies, actually, shot one after the other and in the can, ready to be unveiled to the public.

But the first one — the one that Olsen has been brought to the Georgetown Ritz-Carlton to talk about, and which will open in Washington on Oct. 28 — is very, very good.

It is called “Martha Marcy May Marlene,” a jumbled title that screams “Indie!” rather than “Oscar!” though critics have already wondered if Olsen, 22, might be nominated for one. (“Soulful,” they call her. “Glowy.” “Magnificent.”) She stars as Martha, a woman who falls into a cult — a perverse “Little House on the Prairie” farm fantasy fetish — then claws her way out.

The cult leader, vile and sexy, is played by John Hawkes, whose skulking in last year’s “Winter’s Bone” launched another unknown, Jennifer Lawrence, straight down the red carpet. The bulk of the film takes place after Martha’s escape. She’s living with her estranged sister in Connecticut, lashing out at a family who fears that defending themselves will mean losing her again. She’s ungrateful. She’s weird. She takes off her clothes — a fact that reviews can’t refrain from mentioning — but she does so many nakeder things in the movie that bare skin’s not the half of it.

“There’s such a fear of showing people’s ugliness” in film, Olsen says. She sits in a corner of the Ritz’s restaurant, wearing a white and yellow button-down blouse. It’s very Joan Crawford. Excellent posture from years of ballet. “I was nervous — Martha needs to be likable, because if she’s not, then how are you going to stand by her? But we all have ugly sides, and they usually come out with the wrong people.”

This is the kind of role that would normally be snatched up by Kate Winslet, maybe, or Maggie Gyllenhaal. Some earthy, laconic type whom everyone knows and would expect it from. It is not a role for a new girl.

“You’re not able to read the really good scripts” when you’re just starting out, she says. She does this — says frank things about the way Hollywood works, while managing to sound totally grateful. “You don’t have access to them. No one would consider you — even if it’s an independent film, they need a name to finance the movie. So it was a miracle to me that there was this thing that was that challenging for a young woman. To get to do something like that, it just doesn’t happen.”

But it did happen. It happened with “Martha,” and it happened with “The Silent House,” a smart horror flick, and it happened with “Peace, Love and Misunderstanding,” an ensemble comedy co-starring Jane Fonda and Catherine Keener. After those, she’s got a paranormal thriller with Robert De Niro, a sassy comedy with Allison Janney, and a buddy romp with Dakota Fanning, Dustin Hoffman and Peter Sarsgaard.

The girl who was once nowhere will soon be everywhere, giving performances that are going to take her somewhere, though the destination is still to be determined.

“I saw every girl we could. Between 50 and 75,” writer-director Sean Durkin says by telephone from Toronto, where he, too, is promoting “Martha.” “But Lizzie just had something behind the eyes that was very effortless but intense. She could show a lot without trying too hard.”

After Olsen’s audition, Durkin walked her to the lobby, where he saw that she had a massive pile of luggage — suitcases and backpacks packed for a move upstate. “I was expecting some burly guy to be waiting for her, but she just started loading up herself,” he says. He liked how strong she seemed, how unaffected and real.

Both Olsen and Jennifer Lawrence “are wise beyond their years,” John Hawkes writes in an e-mail. “They’re unafraid of their vulnerability. They both have a healthy way of abandoning the darkness of their characters when the director calls ‘cut.’ ”

* * *

Back to the twins for a second. They were adorable, and then they were gorgeous, then ridiculously gorgeous, and then gross 32-year-old guys started doing things like posting countdown clocks to Ashley and Mary-Kate’s 18th birthday. The world does not make big enough sunglasses to compensate for the gross 32-year-olds of the world.

“They were in the public eye their entire lives,” Olsen says. “And because they were something people grew up with, people thought their privacy didn’t exist.”

Olsen has had her Screen Actors’ Guild card from childhood — she’d done a commercial and some guest spots on her sisters’ shows. She’d auditioned for “Spy Kids.” But when a ballet teacher told her the auditions had made her miss too many rehearsals to dance in the class recital, she decided to stop. “I didn’t have the discipline to only want [to act]. I loved school. I loved sports. I loved singing lessons. I didn’t want acting to feel like a job.”

If she had become a child star, she might not have wanted to become a grownup one.

Acting was back-burnered, then, until Olsen got to NYU as a theater major and started taking classes, learning theory, studying at a conservatory, being responsible. “I thought, if I make sure to do this, this and this, then nobody can say [that I got the part] because of A, B or C. I overcompensated.”

“She took on ‘Electra’ at the end of her first year,” remembers Scott Zigler, who taught her in two classes at the Atlantic Theater Company. “It’s extremely difficult linguistically, and psychologically — she always chose the most difficult material.”

When a teacher told her she should start auditioning, she decided she still wasn’t ready. Instead she did a semester abroad in Russia, then got her real estate license and learned about asbestos code.

“I always say, ‘We still have a seat for you,’ ” says Jared Seligman, wistfully, with a little bit of static in the background like he might be riding in a car. Seligman is the New York real estate wunderkind who hired her for part-time office work and then offered her a full-time job after two weeks. “She has a tremendous work ethic. She was the shining star of our office. If she had stayed in real estate . . . ”

When “Martha” premiered at Sundance, some of Seligman’s clients saw her there, walking on the streets with the regular folk, and asked him why he had sent his staff to a film festival.

Olsen did an interview there, at Sundance. You can find it on YouTube. She sits in a nubby sweater talking with two slightly awkward cinema types, and one of the interviewers mentions that she is on the jury.

“Jury?” Olsen asks pleasantly.

The jury. The jury of people who pick the prizes and are very important.

The fact that she does not know this means that she is more excited to talk about the work than to think about what the work might get her. Lizzie. For real. Come with us. The car is already warmed up. Soothing 1990s road-trip music is waiting.

* * *

“Comedies are harder for me — The quick comedies? The stuff that Emma Stone does? I love watching her because she’s so funny, but it’s something that very few people are able to do really well.”

Olsen is drinking chamomile tea now, and talking about what happens next. Where things go from here.

At Sundance, everyone was giving advice on how to take advantage of the “Martha” buzz. She’s at the place in her career where she can make decisions about the rest of her career.

“It’s a well-known fact for women in this profession that the 20s tend to see the most roles,” says Zigler. “But [Olsen] is like a Laura Linney or a Helen Mirren — she could really make a lasting mark.”

“I think a lot of people make choices thinking that they will put them somewhere,” Olsen says. “And when it doesn’t, they’re disappointed. Right now I’m just trying to be picky. I can’t be too picky, but I can be picky enough.”

Right now she can still decide what kind of famous she’s going to be. It’s a good place — for the most part.

The last scene of “Martha Marcy May Marlene” troubles people. It’s ambiguous. It’s scary. It’s Martha on the verge of something big, but the audience doesn’t know what it is or whether she will come out unscathed. Everyone asks Elizabeth what happens at the ending.

She doesn’t tell them.

What she tells them is this:

“The movie begins in a transition from one place to another, and it ends in transition from one place to another. We go to movies because we want to see wrapped-up stories, but our whole lives are nothing but transitions — people don’t want to accept it [on-screen], but that’s how we are every day.”