Naomi Watts admits playing a mother who falls in love with her son's best friend in the indie film Two Mothers is unconventional.
But she says the story really celebrates women in a powerful way.
Watts took a break from the glitz and glamour of Hollywood's award season to attend the laid-back premiere of the film at the Sundance Film Festival on Friday.
The Australian-French co-production, which was filmed on the NSW mid-north coast, stars Watts and Robin Wright.
Helmed by French director Anne Fontaine, the film sees Watts and Wright portray lifelong friends who fall in love with each other's sons, played by fellow Australian actors Xavier Samuel (Twilight) and James Frecheville.
"One of the beautiful things that drew me into the project was the relationship between the two women," Watts told The Hollywood Reporter while at the film festival in Park City, Utah at the weekend.
"It is so rare that you get a story that celebrates women in such a powerful way with their friendship.
"Usually if there is two women in a film they're usually plotting against each other in some way."
Watts also talked about the importance of having a woman is charge of the film.
"It's a complicated story, not conventional at all but very real and very intense.
"Yes, there is sex in the movie, but it's not about that, it's a symptom of what's going on and I'm just glad it was in the hands of a woman."
The prestigious Sundance Film Festival is held between January 17 and 27.