What do you do when you've got a string of Hollywood credits to your name but prefer working for an avant-garde theatre company? To Bronagh Gallagher, who shot to fame in The Commitments and went on to take roles in Divorcing Jack, Pulp Fiction and Star Wars: the Phantom Menace, the answer is simple: come to the Dublin Theatre Festival, of course. Next month, the Derry-born actress returns to Dublin with a new play staged by Theatre de Complicite: Light

Light is based on a book of the same name by Swedish author, Torgny Lindgren. It tells the story of a village ravaged by plague and the seven characters left alive who struggle to survive and sustain order in the village. Bronagh Gallagher plays the part of the sole surviving daughter of the elder of the village. She has lost her mother and brother and, left alone with her father, the question of an heir looms in the most sinister way.

"This play is a massive, massive play and it's about choice and it's about law and order and people's inner belief that we need law, justice and order. And the choices we make dictate the quality of our life and the whole show changes every night", Gallagher explained. Actor Brian Cox once said to Derry-born Gallagher that she has an obsession with injustice and he's right: "Where I come from, the demand for truth and justice was huge".

Gallagher is no stranger to playing demanding roles. The last stage role she played was Mary in the Royal Court's production of Conor Mc Pherson's Dublin Carol. "I played the child of an alcoholic and it was a really sad and lonely character. I met Geraldine McEwan and she said to me that with a character like that you don't walk away from it, you live with it. I realised that this was what was happening." She says she is looking forward to seeing Dublin Carol at this year's Dublin Theatre Festival.

"It's a great part for a woman and I think it's a wonderfully observed beautiful piece of writing about the loss of people in your life through alcoholism."

Light is a more self-consciously artistic play and therefore one that actors don't become part of in the same way. "It's very masque-like," Gallagher says. "You use the body almost vocally. Simon McBurney (co-founder and artistic director of Theatre de Complicite) has developed a new theatrical language for the company. He is a master of physical movement and how the body moves. It's a style that he is crafting. You see Peter Brook using actors in the same way."

The focus on movement is no mere theatrical nicety. The actors spend an hour each morning doing yoga and then spend time playing ball and completing other physical tasks to achieve complicite within the group.

"This is about complete clarity between your body and mind and you have to be clear with this group. You become fit physically and look fit. Therefore you are able to stand on a stage and every part of your body is out there. The body is as important as the mouth."

But that's the least of the play's peculiarities. It is constantly being developed. "The play that will be seen in Manchester will not be the same play as is put on in Dublin," says Gallagher. "We are a team of archaeologists and we are digging and excavating this piece of work and we still have a long way to go.

"Complicite's work never ends. It never ends and that's what I love about it, it's constantly digging. And it's very musical, which is why I love it so much, because music is probably the thing I love most. We all sing different, beautiful songs in the play. It's all about timing; it's very rhythmical. My big love is rhythm and drums. Complicite is like a really crazy vaudeville orchestra and everybody plays a weird, wacky instrument. You get to experiment with your voice and your body as an instrument."

Between her last two theatrical roles, Gallagher has worked on the new BBC sitcom, The Fitz. "I was working with a great bunch, Deirdre O'Kane, D'Unbelievables, Eamonn Morrissey. I know there were mixed views in Ireland but what it was a farce, a bit of crack, and I know many houses in Ireland like that. And after three months at the Royal Court doing a play about alcoholism, I needed to have a good giggle."

"Success is a funny word to me. What is it? Other people's perception of your work. The truth is that I've had such good opportunities"

For one so successful, she is surprisingly modest, and very upbeat and positive. She says in her down-to-earth way: "Success is a funny word to me. What is it? Other people's perception of your work. The truth is that I've had such good opportunities".

She laughs at the idea of herself as a Hollywood actress. She was in Los Angeles seeing friends at the time of the casting of Pulp Fiction, "and they kept ringing me because they wanted to give me a part. Quentin (Tarrantino) said to me we really want you to be in it, whatever happens, and he kept his word".

Gallagher hasn't given up on films altogether. She was back in Northern Ireland last year working on Wild about Harry, shortly to be released. "There we were with mostly an Irish crew from North, south, east and west. It was absolutely fantastic to work in cinema in Northern Ireland. When I was asked to do it, I just thought, yes, I'm going home and I did it."

But theatre remains her first love: "I love Complicite because it challenges everything and it's so rewarding".

Light runs at the Gaiety Theatre October 11th-14th at 8 p.m. There will be a matinee on October 14th at 2 p.m.