Like most people, playwright Enda Walsh was horrified by news reports earlier this year of the arrest of Joseph Fritzl, the Austrian who imprisoned his daughter for 24 years. Unlike most people, however, Walsh felt a troubled sense of familiarity, a connection, with the story. “I thought, ‘Oh my God, that’s my territory. This is my plays.’”

He isn’t exaggerating. The Walworth Farce, which opens at the National Theatre in London next week (Sept 25), focuses on a tyrannical Irishman who has kept his two sons locked in a decrepit flat since the trio arrived in London almost two decades before. In The New Electric Ballroom, a hit at this year’s Edinburgh Fringe, a woman is so controlled by her two older sisters that, at the age of 40, she has yet to be kissed. Most chillingly, Walsh’s 2000 play, Bedbound, depicted a young woman who has polio living hugger-mugger with her flamboyant father, in a space little bigger than a double bed.

Despite the mesmerising poetry of his writing, and its flashes of savage humour, Walsh’s plays are tough to watch – which is, the exuberant 41-year-old thinks, as it should be. “People either connect with my plays or they go….” He’s often amused by the responses of critics, who question the plausibility of his characters’ experiences. Fritzl’s story almost made him want to “jump in the air and say, ‘See, they’re not that weird,’” he says. “There was a review of The Walworth Farce that said, ‘Surely social services would have got on to these two boys?’ What are you talking about? This is theatre!”

For Dublin-born Walsh, avoiding naturalism is written into his “Irish playwright DNA”. “I don’t like seeing everyday life on stage: it’s boring. I like my plays to exist in an abstract, expressionistic world: the audience has to learn its rules, and then connect with these characters who are, on the surface, dreadful monsters.” If he feels a strong connection with his grotesque characters, it’s partly because they are reflections of himself. The violent Bedbound was about “me finding a real love for my father”; the daughter’s pell-mell use of language was a twisted amplification of Walsh’s own. He talks rapidly, hurling out expletives and self-deprecating quips.

His characters are often locked in bizarre routines, repeatedly forcing themselves to re-enact upsetting scenes from the past. This, too, mirrors Walsh’s life: 10 years ago, he experienced two years of “panic attacks and borderline obsessive compulsive disorder”. If he didn’t drink a glass of water at the exact same time every day, or visit the same cafe for exactly the same lunch, he would plunge into panic. “At the time it was exhilarating,” he confesses. “It affected my writing for eight years, in terms of characters having to live like that.”

Walsh cherishes the fact that, before his father’s death from cancer in 2000, he told his son that he was “proud of the fact that I wrote hard plays; that I was hard on humanity”. Although he probably inherited a theatre gene from his mother, who acted at the Abbey and Gate theatres in Dublin before her four sons and two daughters were born, he says his father inspired his love of drama. A salesman, slowly ruined by the 1980s recession, he was “a great actor. He had a huge shop, and the way he worked the room was really impressive.” Walsh initially studied film, a decision he admits was perverse. “Ireland has no film industry: it’s like studying dentistry in a country where people have no teeth.” But his time wasn’t totally wasted: in 2001 he turned his breakthrough play Disco Pigs into a movie, and Hunger, the film he co-wrote with director Steve McQueen, won the Camera d’Or prize at the Cannes festival this year.

Although he knew he wanted to write, Walsh says that plays came as a bit of a shock to him. In his mid-20s, he moved to Cork and fell in with a fledgling theatre company, Corcadorca. “I think we thought we were in a rock band. We used to put tickets in people’s doors and get them into these terrible devised shows. Then we’d sit down with the audience and say, ‘That was shit, but why was it shit?’” After four years of this, he learned how to write a decent play.

Walsh might have stayed in Cork, only in 1997 he started dating a Londoner, Vogue features editor Jo Ellison. He relocated from Cork to London, where the couple married and now live with their three-year-old daughter. The city has had a profound effect on Walsh’s writing. “The Walworth Farce was the first piece I wrote here, and I really enjoyed the pressure of sitting at my desk in London thinking, ‘Right, I’d better arrive on the page here, because this city is huge and it’ll gobble you up.’ The risk of getting up in the morning and living a life is still something that catches my breath.”

This is how his characters experience life. We catch them just as “they stop and go, ‘Phew, I still exist. Do I want to exist in this way? No, I want to exist in another way.’” He knows it can be painful to watch them puzzle this out. “But that’s the role of the playwright,” he says. “To highlight the detail of life, the seconds of thinking that we’re all skin and bone and chemicals and memories. The characters remind us to stop for a bit”.—Dawn/Guardian News Service