THEPERFORMANCE

FOR MAGGIE Gyllenhaal, it’s tough being a working mom, but not because of the demands of her and fiancee Peter Sarsgaard’s 21-month-old daughter, Ramona. It’s the interest the new baby draws.

“The paparazzi were just really awful to us,” she says. “I mean, they called the fire department and told them there was a fire in our little, tiny building in the West Village so that we would have to come outside with a 5-day-old baby. So all of that was happening and I was trying to navigate my way through that when this offer [to play Rachel Dawes in ‘The Dark Knight’] came. And so I thought, ‘It’s going to push that stuff further probably.’ But what am I going to do? I’m going to hide and not do things that are appealing to me? I’m an actress.”

Immediately preceding the film’s release, no one’s crying fire as Gyllenhaal nibbles a papaya and sips a pot of green tea during breakfast in the restaurant at Santa Monica’s Casa Del Mar. But the 30-year-old indie darling’s fears are nevertheless well-founded as she dives into the publicity campaign for the biggest film she has appeared in to date -- and one rife with tragedy and complexity.

When it comes to the most difficult of these -- her costar Heath Ledger’s death a mere two months after the film wrapped -- Gyllenhaal speaks with candor about the actor’s mental state while playing the sociopathic Joker. “For every actor, you can get to this special place with a character where nothing you can do is wrong, where you just are living that person,” she says. “That’s what happened with Heath. And I would say it’s difficult to be that good in a movie that big, where it’s about a lot of other things aside from the acting. So he really accomplished something amazing. You know, I couldn’t really watch him and when I first saw him on screen I felt very emotional.”

Signing onto the film also sparked a minor media circus, since Gyllenhaal was taking over the role from Katie Holmes, who had dropped out months earlier due to “scheduling conflicts.” Speculation ran wild that Holmes was ousted from the franchise for bad reviews or possibly her status as Mrs. Tom Cruise.

But Gyllenhaal was committed to making the character her own from the very first time she read the script -- at her brother Jake’s house with a man standing guard in the driveway to make sure that she wouldn’t run off with the franchise’s secrets. “When [director and co-writer] Chris Nolan gave me the script, he said, ‘She’s not quite finished yet,’ ” Gyllenhaal says of the character. “So I read it, and I had a lot of ideas about ways that I thought that she could be stronger. And he was very open and collaborative and interested. In that first preliminary conversation, a lot of things that we talked about ended up in the movie. It was really trying to find a way that I was absolutely in love with Harvey Dent and absolutely in love with Bruce Wayne, the ways I found them both honorable, ethical, moral men and the ways that I had problems with their ethics and morals.”

Gyllenhaal has earned two Golden Globe nominations -- for roles as the masochistic new hire in “Secretary” and the heroin-addicted mother in “Sherrybaby” -- and appeared in bigger budget fare like “Stranger Than Fiction” and “World Trade Center.”

“When I started acting [in 2000], you could make an independent movie for $5 million and pretty easily get it financed with one sort-of-known actor in it,” she recalls. “That is not true anymore unless you’re making broad comedy or thriller or horror films. I’ve been thinking about how to get the things that are interesting to me made. So at the moment, I’m getting interested in what I guess you would call producing.”

Rather than struggling to strike balance in her life as a new mother and an actress, she’s integrating the two. She recently wrapped another high-profile project, director Sam Mendes’ “Farlanders,” a comedy about a couple in search of the perfect place to raise a baby. “I got to set my first day and I thought, ‘I haven’t worked in a long time. I’ve just been with my daughter,’ ” Gyllenhaal says. “And in the scene, I was acting with a 4-year-old and an 11-month-old. So there were two 11-month-old twins, and they were hysterical the entire day. And so I ended up mommying. You know, the calming, the baby bouncing, giving the baby its pacifier.”

She smiles, calm and a little sleep-deprived. “If I weren’t a mom, I never would have been able to do it.”