In Pablo Larraín’s unsettling film, Mariana Di Girolamo stars as a dancer who finds freedom through reggaeton dance.Ema is the oddest of things: a dancer with a passion for setting things on fire. In “Ema,” Pablo Larraín’s film, the title character has a particular look, too: bleached hair slicked back so severely that it appears to be shellacked to her head. That hairstyle, hard and impenetrable, is like a coat of armor, which makes sense. Ema is made of ice. Until she dances.Set in the coastal city of Valparaíso in Chile, “Ema,” now in theaters and on Amazon and other digital platforms starting Sept. 14, tells the story of a couple, an older choreographer and a younger dancer — Gastón (Gael García Bernal) and Ema (Mariana Di Girolamo) — who adopted but then abandoned a Colombian boy named Polo. The reason they give up the boy turns out to have something to do with fire; he’s fond of it. It’s not hard to draw conclusions about who might have encouraged him.Ema is a member of her husband’s experimental dance company, and it’s no secret that she has lost interest in it — and in him. Her obsession is reggaeton and its dance, which she relishes for its aggressive sensuality; outside of the dance studio with her friends, her body is electric as she lets her limbs fly and her hips shake. Gastón is not impressed. To him, reggaeton is music to listen to in prison, “to forget about the bars you have in front of you.”Their generation gap is apparent as Gastón continues: “It’s a hypnotic rhythm that turns you into a fool. It’s an illusion of freedom.”Moving like a unit: A scene from “Ema,” with choreography by José Vidal.Music Box FilmsIs it? Who is Ema? She gave up her son, but seems to want him back. She’s a seductress who carries — and uses — her body with steely, precise intention. While her inner world is a mystery, it’s clear what reggaeton allows her to feel: free.Dance is the key. But unlike so many films and television series of late, it isn’t a superficial layer tacked onto the story. In “Ema,” Larraín, the director of “Jackie” and the coming “Spencer,” has given dance, or movement, a leading role. It’s also a means to an end that extends beyond conventional choreography: How can dance bring Ema closer to freedom? Whether she is alone or with her friends — a collective body moving as one — her physicality spreads across every scene. And she doesn’t even have to be moving: Her inner vibrations are just as lucid in stillness.Because of that, the film, with its dreamlike score, is something of a dance, too — floating, gliding and then, all of a sudden, turning on a dime. “Ema” is an action film, but not in the conventional sense: The body is the action. And while there is dialogue, words add up to less than the deliberate pacing of each scene and the poetic power of Di Girolamo’s frame.In a magnetic solo at the port, dusky light envelops Di Girolamo’s silhouette as she stands with her back to us and her legs wide apart. Her right arm, bent at the elbow, is raised, her hand in a fist. Rocking her hips, she swings from side to side as her arms open and close. It is hypnotic, but she’s no fool. She’s strong and tenacious; you sense the tension leaving her body through her dance.Di Girolamo in a dance scene at the port in “Ema.”Music Box FilmsAs she picks up the pace, walking with purpose and changing direction, her back undulates and her angled arms carve through the air to an imaginary beat. Moments later, she’s on a carousel ride, but there are echoes of her dance: As she grips her horse’s pole, she sways, dipping from side to side; she’s almost relaxed.Once she stops moving, her expression changes: Her thick brows frame a stony face. She is catlike with the kind of stare that makes you feel invisible; at the same time, she dances as if you were invisible. She’s beyond needing an audience.Di Girolamo is not a trained dancer, though she studied flamenco for a few months as a teenager. Her mother decided she would be better off doing that than being in therapy. “It was literally a therapy for me,” Di Girolamo said in a recent Zoom interview. “It gave me the necessary tools to be empowered and to continue ahead.”But she does love to dance. (Her husband is a D.J.) In “Ema,” she had tools to help her body acclimate to her character: One was the hair, which helped her to see Ema as an energy — like the sun, like fire. “She’s very hypnotic, and in some ways she’s very dangerous or destructive,” Di Girolamo said, “but you also want to be close to her.”“She’s very hypnotic, and in some ways she’s very dangerous or destructive,” Di Girolamo said of Ema, “but you also want to be close to her.”Music Box FilmsThe other was her training. Di Girolamo worked closely with the Chilean choreographer José Vidal, whose company appears in the film. Mónica Valenzuela was also part of the choreographic team, and her focus had more to do with the reggaeton moments. “I think Pablo wanted more of a nasty movement that I wasn’t apparently quite able to find,” Vidal said with a laugh, in an interview. “So she came to add some spice. It’s not like there is phrase one, phrase two — it is a mix of all of the materials.”Vidal’s choreographic approach involved studying Di Girolamo’s mobility: the flexibility of her spine, the range of her arms. He then turned that into a language. “More of a street dance, reggaeton sort of thing,” he said. “But it never came directly from that. My intention was, OK, we’re going arrive there. But we’re going to arrive there coming from an inside place.”The process began with immersive work that helped Di Girolamo to “connect into herself, into her emotions, into her structure,” Vidal said. “How does it feel to move here” — he patted his chest and swayed his shoulders — “and what connects you with each emotion? It was never about making her imitate or repeat something directly.”Vidal on the set. To choreograph for Di Girolamo, he studied her mobility and turned it into a language.via FabulaDi Girolamo also had to blend in with the professional dancers in Vidal’s company. The opening scene features an excerpt from his “Rito de Primavera,” inspired by “The Rite of Spring.” To dance in it, Di Girolamo studied ballet and Pilates. “I don’t have very good posture, so we worked on it,” she said. “I had to understand the limits and the possibilities of my body.”That led her to find Ema’s physicality — her rhythmic, weighted walk and the way she invades space both to intimidate and to get what she wants. “Dance was very important for me to understand how she seduces the other characters,” Di Girolamo said. “It’s the tool she has, and she’s conscious about that tool.”She spent a lot of time on the floor breathing. Vidal called it an initiation into the body, into the movement. In addressing her posture, Vidal focused on opening her chest, which in turn paved the way to showing her tasting freedom, even being vulnerable. There’s a reason the scene at the port feels so fresh and spontaneous.“I remember it was very cold, and Pablo said, ‘Mariana, now you have to improvise a dance scene,’” Di Girolama said. “I was like, what? But I started dancing. I used the same steps of the choreography, but I deconstructed them. I’m not very good at improvisation, but if I have some tools, some things that I know, I can do something with it. I kind of deconstructed the choreography to make a new one.”It wasn’t easy. “I was very nervous,” she said. “It’s like singing. It’s a very personal thing. It’s like a window of our souls.” More