By Nancy Mills, Hollywood

Kate Winslet says she does not look back when she evaluates her career, or wraps up the final details of her impending divorce. "I go for it and have no regrets," she says, her jaw firmly set and her eyes focused intently on her interviewer. "That's my motto. That's also Iris' motto."

She is speaking of Iris Murdoch, whose heyday and decline are chronicled in "Iris," this year's actor-driven Oscar candidate from Miramax. Winslet plays Murdoch as a free-spirited prodigy at Oxford and Judi Dench plays her in her 70s as Alzheimer's Disease robs her of her powers.

Murdoch is unfamiliar to many Americans, but the Anglo-Irish writer is a legend in Britain. In fact, until her death two years ago, she was frequently described as "the most brilliant woman in England." She lectured on philosophy at Oxford and wrote 26 penetrating, genre-busting novels that have been described as "psychological detective stories portraying complicated and sophisticated sexual relationships."

The most intriguing aspect of Murdoch's life was her 43-year marriage to literary critic John Bayley. They lived happily together, without children, until 1997, when she was diagnosed with Alzheimer's. Bayley, who until then had been the subordinate partner, suddenly found himself looking after a woman who was rapidly disappearing into herself.

He wrote in his memoirs about their early days: "It's like living in a fairy story. I'm the young man in love with a beautiful maiden who disappears to an unknown and mysterious world every now and again."

"Iris clearly didn't regret things or wallow in sad emotions," Winslet says. "She very much got on with it. She always saw the inner beauty in people. I think that's very similar to me."

"Iris," directed by Richard Eyre and opening Dec. 14, alternates in time between Bayley's timid courtship of Murdoch at Oxford and his frustrated attempts to preserve some normalcy in the dark days of her decline. As Bayley, whose memoirs are the basis for the film, Hugh Bonneville plays opposite Winslet and Jim Broadbent opposite Dench.

"It's a genuine love story about two people who absolutely adored and accepted each other for everything they were," Winslet says. "It's not about Alzheimer's, although that side of the story is simply the tragic truth of what did actually happen to this wonderful woman. It's more about the incredible love, commitment and support that John Bayley gave to her when she was suffering."

Although Winslet is on-screen for less than half the film, she imbues her scenes with Murdoch's enormous zest for life. Whether she is arguing a literary point over lunch, swimming naked in a pond or bicycling madly down a country lane with Bayley in pursuit, the dazzling young author is a free spirit.

"Iris had an amazing ability to be in touch with her emotions and not judge herself," says Winslet, who watched documentaries about Murdoch and TV interviews and also immersed herself in Bayley's memoirs. "She was really a person who saw the good things in life."

It was Eyre's idea to cast Winslet as the young Murdoch. "Kate in some way was like a clone and an alter ego of Judi [Dench]," he says. "They both have an identical spirit, which harmonizes perfectly. Kate's a very mature and thoughtful woman, and her greatest strength is similar to Judi's - her humanity."

Winslet was "honored" and "challenged" to share the role with Dench. "We didn't talk beforehand about how we would walk or speak," she says. "But I did watch a couple of scenes that Judi shot so I could get a little sense of what she was doing."

"Iris" gave Winslet her first real opportunity to play an fully adult woman. "I play Iris at about 30, and I'm 26," she says. "I've always been told I'm wiser than my years, so I didn't find that so difficult. But I did worry because she's obviously far more intelligent and intellectual than I am. But writing was wonderful and her level of intellect was built into the dialogue."