Haunting fjord-blue eyes gaze into the distance from the poster of the latest Ibsen offering staged by the Arcola Theatre, London. The eyes belong to the award-winning actor Lia Williams. No stranger to the representation of intense introspection and emotional trauma, Williams is starring as arguably the most enigmatic of Ibsen's motherless young female protagonists -- Ellida Wangel. Motherless indeed, although, as we later learn, Ellida's own experience of motherhood has been as tragically short as her memories of her birth-mother, whose mental instability threatens to represent a self-fulfilling legacy for her unfortunate daughter. All who have experienced the loss of a child will empathize with this chillingly evocative character, written with remarkable insight by the sixty year-old Ibsen.

I meet with Williams during a well-earned lunch break during rehearsals. Elegant and intense, witheringly beautiful and electrifyingly serene, Williams discusses the play, her personal ambitions, and her relationship with the play's adaptor, Frank McGuinness. "I first met Frank in 2001," Williams notes, "when he came to see me working in The Homecoming at the Gate Theatre, Dublin." Playing 'Ruth' to Ian Holm's 'Max' and directed by Robin Lefevre, Williams remembers this experience with obvious fondness. "It was at this time that Frank said that I was born to play Ellida in The Lady from the Sea -- and he decided to adapt the part for me." As Williams admits, however, both their creative energies "got very busy," and the project simmered away in the background.

In 2003, Williams established her starring credentials further by winning the Irish Times ESB Irish Theatre Award for Best Actress in Tennessee Williams's The Eccentricities of a Nightingale, with Williams playing the emotionally-charged Alma Winemiller. This led to her working as Rosalind in a stunning version of As You Like It for the RSC, directed by Dominic Cooke, and it was in this production she met Hannah Eidenow, the director of the joint Arcola Theatre and Silkensaw production of The Lady from the Sea. "After all these years of wanting to work together, Frank and I have finally brought this wonderful play to the Arcola stage."

There is little doubt that, as much as Frank McGuinness respects Lia Williams, that respect is returned in equal measure. "When I first saw Frank's version," Williams comments with true admiration and excitement, "I thought it was absolutely beautiful and poetic and fierce and funny." It is the 'fierceness' of McGuinness's adaptation which seems to act as a trigger for Williams. "It is a play about a woman's fierce struggle for individuality. There's a fundamental desire that we don't hide whatever personal truth we have -- society presents a series of lies that we live by, and [Ellida] systematically breaks these down."

Williams obviously admires Ellida on a deeply visceral level. "She is the bravest woman you've ever known." Showing great generosity, Williams proffers me her personal rehearsal script and points to the notes she has scribbled about her character's personality. These fascinating insights into the process of character assimilation speak volumes about Williams's own interpretation of the part. Two sentences pencilled on the title-page stand out. 'An emphatic defence of individuality' appears to represent Williams's attitude to Ibsen's play as a whole, whilst 'The fear of her own capability' provides the underlying motive force for Ellida's tortured existence, sexual inhibition and passion, and mental unease.

Williams explains the 'fear-of-her-own-capability' observation. "[Ellida's] afraid of what she can do, rather than what she can't do -- she is definitely on the brink of self-destruction." Apparently without recognizing the fascinating significance of the comment, Williams describes how she discussed the role with a psychotherapist. "When people are breaking down," she explains, "they're really breaking through. A nervous breakdown could be considered, often is considered, a collapse -- but it is also a process of recognizing who or what you are and of finding a road to recovery." For an actor who is renowned for her brave confrontation of mental collapse as a representational aspect of performance, these are insightful comments into the practical discovery of a role.

"It was a conscious decision on my part to approach a psychotherapist. I think it is so important for an actor to spend at least half the time researching -- it helps you find a springboard. When you are out there, in front of an audience, you are less exposed the more you surround yourself with information." More importantly, for Williams, is that it makes her and any actor's performance "more truthful." "Research is fascinating -- finding out about people."

Williams is certainly aware of the Freudian implications not only of her role, but also of Ibsen's writing as a whole. As she explains, Freud was himself fascinated by Ibsen's plays, using them as examples for his later character analyses and also as dramatic texts with which to illustrate his own theories. "Freud even learned Norwegian to read Ibsen," Williams notes with obvious admiration. The Lady from the Sea was written in 1888, a decade before Freud began formulating his arguments. There is no doubt that Ibsen was expressing on the stage the sexual and psychological problems of society which were to lead to our modern concept of Freudian psychoanalysis. Who knows, without Ibsen, perhaps we might never have understood an Oedipus complex?

"I don't think the play has dated," Williams adds, "human beings still struggle for freedom. Ibsen put this struggle into words, but they were instinctive words, based on an innate psychological insight." Receptiveness to this innate insight is the key to Williams's interpretation of Ellida. "What overwhelmingly comes across in this play is its humanity," she explains. "If we live truthfully with each other and responsibly for ourselves we will do well."

"Because we live in a cynical, ephemeral, surface age, we run the risk of losing that sense of poetry and of finding ourselves." With Frank McGuinness reinterpreting this magnificent play, Lia Williams feels confident that the 'sense of poetry' that is The Lady from the Sea has been reborn, in a play for which the "huge themes of love and humanity can only make you fell better about the world you live in." Sensuality and eroticism and the fearful reawakening of old wounds and lust -- utterly irresistible theatre.