Limerick native Ruth Negga, 34, makes her powerful international debut in the surefire award winner "Loving," opening Friday. The gripping tale of a marriage that changed America, Negga plays an African American woman married to a white man (Joel Edgerton) as they defy the racial ban on marriage in Virginia in 1958. Cahir O’Doherty review this deeply moving new film and catches Negga’s star-making turn.

About five minutes into "Loving," the powerfully moving new film that tells the true story of how one interracial marriage changed America, Ruth Negga makes a seamless transition from up and coming Irish actress to breakout movie star.

It’s not something you see very often in films, so you notice it when it happens. Onscreen Negga inhabits her character like any good actor would, but she doesn’t just play the role. She gives an unforgettable performance, one that will haunt you for a long time after you witness it.

"Loving" is based on the real life experiences of Mildred and Richard Loving (their last name is one of the ironies of history) who were fated to meet and fall in love in Virginia in 1958, a time and place deeply hostile to interracial relationships, never mind marriages.

You might expect, given the subject matter, to be beat over the head for two hours with a blunt 'good versus evil' morality tale, but all this unfortunate couple wants to do is get hitched and stay together.

By focusing on the central relationship (powerfully performed by Negga and Joel Edgerton) director Jeff Nichols lets the characters speak for themselves, and in the process he creates something much more understated and compelling, a portrait of a long marriage that’s as moving as it is real.

With her eyes like a lighthouse pulling you into every scene, Negga is never less than riveting. She makes us feel the ever-present threat the couple lives under, and she makes us understand what that can do to ordinary people forced to contend with extraordinary circumstances.

As "Loving" opens we meet an anxious Mildred on the point of revealing to her lover Richard that she’s pregnant. Fearful of his rejection, she’s instead bowled over to hear that, a construction worker by trade, he plans to build a house and marry her.

This was a highly unusual development in the late 1950s in the South, where hostility to interracial relationships was such that being in one could get you fired, ostracized and even killed.

Contrast this kind of daily tension with the sheer ordinariness of the love between the pair and you begin to understand the atmosphere of "Loving." This was not a fight that Mildred and Richard ever picked, because you can’t help who you fall for, but now that it’s happened they’ll be damned if they give their happiness up because their racist neighbors would prefer it.

Watching Negga move though this film is a bit like watching one of the great leading ladies of the golden age of Hollywood.  I was startled by the power and the artistry of her multilayered portrait, and I was not at all surprised to hear that her she’s a fan of Bette Davis.

“Bette Davis is my hero,” she told The Guardian. “I’m obsessed with her. I base everything I do on her. She’s one of those people – like Bowie or Jimi Hendrix – who seem to say, ‘Look, you’re okay. You’re cracked, but you’re okay.’”

When Irish director Niall Jordan first saw Negga act he changed the script of his film "Breakfast On Pluto" just to include her in it. When you see "Loving" you’ll understand immediately what he saw in her.

Raised in Limerick, Negga was born in Addis Ababa in 1982 to an Irish mother and an Ethiopian father. Tragically, her father was killed in a car accident when she was seven. Years later she attended the famed Samuel Beckett Center at Trinity College Dublin where her talent was immediately spotted.

But from her first big role in Jordan’s 2005 film she has, she says herself, taken a somewhat leisurely stroll toward stardom. Call it a decade long case of overnight success. Watching her onscreen you can see a complex inner life, so it’s not a shock that the complexity spills over into her work.

“Partly my feelings of difference were down to having parents of different races,” she told the press, reflecting on her childhood. “I had quite a scattered childhood. I was Irish in London, because I had my secondary school education there. I never really fitted anywhere. I didn’t feel it was a negative thing and I was never made to feel different – I just knew I was.”

The sense of being a little different has drawn Negga toward characters on the margins, to non-flashy people who might otherwise not get a hearing. She portrays all the complexity and beauty that was overlooked, and the surprise of it can hit you like a meteor strike.

“Mildred shied away from the spotlight completely, but she changed the course of American legal history,” says Negga. “All she wanted to do was marry the man she loved. It took nine years. Can you imagine taking on the might of the American legal system? They were poor and fairly uneducated, but they just wanted to be with one another.”

The thing that "Loving" gets absolutely right, in every frame of this exceptional film, is the quiet but devoted love between its determined husband and wife.  I have rarely seen a long marriage more convincingly portrayed on the big screen.

In each scene Negga is in, she manages to convey a great deal of information with just a careful glance at Edgerton, who matches her look for look, so much so that you can’t take your eyes off the pair of them. It feels so personal it’s almost as if you’re eavesdropping.

Negga’s the emotional center of the film from the first frame to the last and she’s so careful with the material, and with the story the film is telling, that you can’t help but be swept up by the adventure they’re on.

"Loving" is Oscar material of the highest order, so I’ll be surprised not to see the two leads nominated for what is, to me, the most affecting love story I’ve seen on the big screen since Ang Lee’s "Brokeback Mountain" in 2005.

Growing up in Ireland helped Negga get her head around the tensions that are portrayed in the film, she says, in a confession that any Irish immigrant can relate to.

“Virginia isn’t that different from Ireland. Land and home and community are super important,” Negga said.

“When I was playing her, I tried to imagine I couldn’t go home again because of whom I married. It must have drained the lifeblood from her.”

Negga was conscious of being different growing up in Ireland, but she didn’t experience racism until she moved to London.

“When I was a kid in Ireland, there were not very many black people. I was very much like the strange brown thing, intriguing and cute,” she recalls.

“I didn’t experience racism there. The first time I did was in London. It was that moment you realize you’re black. A kind of lifting of the veil.”

In "Loving" the veil is also lifted on the power of love to fight racism all the way to the Unlisted States Supreme Court to clear a space for itself. By the end of the film, and Negga’s megawatt central performance, you’ll come away moved and inspired.