Julianne Moore plays a miserable '50s housewife reading the book, Meryl Streep plays a modern-day "Mrs. Dalloway" and Nicole Kidman plays Virginia Woolf as she struggles to write it.
"Some people have sat through the whole movie and not known it was me, which is really great," says Kidman.
For Early Show co-anchor Harry Smith, her transformation was not so much physical as emotional -- full of power and frailty.
"I just fell in love with her," Kidman says of Virginia Woolf. "I just felt, this woman is such a magnificent creature, and such an unusual artist. So I think ,in some weird way, when you're taking somebody else's skin who's lived and existed, and particularly had the struggle of life that she's had then done this great work, it stays with you. Something happens."
But becoming Woolf was not something like flicking a switch for Kidman.
"I wish," she says with a laugh. "I wish I could do the flick-a-switch thing, because it would make my life a lot easier. But I think that's what draws me to acting as well, that there is this sense (that) you get to embody, be another person. It's like layer upon layer. You hope that it will just bloom, rather than hitting for an actual result of what you want to achieve."
As for the work of the rest of the cast, Kidman says it filled her with love.
"Usually, I can't sit through my own films, because you cringe, especially if you're in every scene. And I'm not in every scene in this film. So I get to watch Meryl Streep and Julianne Moore, two of the greatest actresses, doing their thing, you know. And I just look at it and I look at it with love. Because I think, wow, we got to make this together," says Kidman.
As for her family life, Kidman says it is part of her children's education to visit her on the sets and seeing what she does and how she looks. They were on the set of "Moulin Rouge."
"Looks like top hat and corsets and high heels and fish nets. And they go, 'Mommy!'" says Kidman laughing. "And then Mommy in [The Hours] is wearing a strange nose. So they just go, 'Oh, crazy Mommy.' They're always like, 'Our Mom, loves to sort of you know, change the way she looks.'"
There have been many articles written about Kidman in the last two years. And the one thing Smith says he was taken aback was that after the breakup with Tom Cruise, she wasn't sure she going to work again. Or she wasn't sure that people would want to see her.
"I think a lot of me is very defined by Thomas. And, therefore, I felt like I didn't really have my own life and my own career, which is normal when you're married to somebody and you spend an enormous amount of time with them, they're sort of at the center of your world. So in terms of that, yeah, I just felt like where is my place in the world now, really," says Kidman.
Certainly a lot of definition coming from "Moulin Rouge" to "The Hours."
"I've been very fortunate. Strange, the way life plays those tricks on you. And you know, you get one thing and something else goes away. And so luckily, though, I had an enormous amount of support from my friends and from the people that I work with," she notes.
And people are talking about a probable Academy Award nomination.
"Well, I got nominated for the first time last year for 'Moulin Rouge.' And that was a lot of fun, I've got to say," she says with a laugh.
"I mean, it's kind of like you're invited to the prom. But I think for this movie, that's different, because 'Moulin Rouge,' it was like, we'd already released 'Moulin Rouge.' And so it was kind of like the end of a very, very long particularly hard year. And with this film, though, it's more like this film's coming out. And so we need the support and the critical support. And anything that helps so the people will go see the film. I think it's where you go, 'Oh! That would be nice,'" Kidman adds.