PARK CITY - Since premiering on Friday evening, steamy romantic melodrama "Two Mothers" has been one of the most talked-about titles of this year's Sundance Film Festival -- even if it doesn't have all the critics on its side. At the screening, audience reactions ranged from stunned gasps to nervous laughter at the film's highly unorthodox relationship study.

Set in idyllic coastal Australia, the film stars Naomi Watts and Robin Wright as two lifelong best friends who, as they approach middle age, both find themselves sexually entangled with younger men. Well, that's burying the lede a little: the man in each case is the other woman's teenage son.

Based on a novella by Nobel Prize-winning author Doris Lessing, it's a story that's equally likely to be called brave or ludicrous, but Watts and French writer-director Anne Fontaine ("Coco Before Chanel") went into the project expecting heated reactions. Grabbing some time with Watts and Fontaine at Sundance today, I spoke to the pair about their own relationship to this complicated love story.

Watts, for whom promoting a new film in Park City comes as a brief respite from the Oscar campaign trail -- in case you'd forgotten, she's nominated for Best Actress for her performance as a very different kind of devoted mother in "The Impossible" -- responded immediately to the script, but admits it was a process moving from "shock" to "a place of forgiveness" with her character.

Fontaine, meanwhile, relished the story's unconventionalities, as well as the chance to move outside her comfort zone by directing her first English-language film: she'd originally conceived it as a French adaptation, but soon felt the story required an Anglo-Saxon context.

Meanwhile, if the film was a foreign adventure for its director, it was something of a homecoming for Watts: as the Australian star explains, "Two Mothers" marks her first film in her native country in a decade. As much as she enjoyed acting in her natural accent for a change, however, Watt's doesn't mind admitting it was harder to locate that accent than you might think -- a small additional challenge to a role not short of bigger ones.

Watch the complete interview above.