Cate Blanchett, who recently gave birth to a son, Dashiell John, might have avoided the daunting physical challenges she faced in Charlotte Gray if she had confessed during filming that she was preggers. But Blanchett soldiered on, playing a Scottish woman who goes behind enemy lines to join the French Resistance in World War II.

"I didn't tell anyone at first, not even Gillian Armstrong, the director," she reveals to TV Guide Online. "It wasn't their fault, and I wanted to do my job. But it was bloody cold, the worst winter in Britain in years, and the first week we had to go through this really nasty military obstacle course."

At least Blanchett — whose performance in

Bandits earned her a 2002 Golden Globe nod for best actress in a comedy or musical — managed to avoid a scene that called for her character to parachute into occupied France. "I'm in practically every frame in the film, and the producers were paranoid that I might get hurt and mess up the schedule," she says. "I was thankful for that. I think I'd do almost anything for work, but I don't know if I would jump out of a plane."

Just to prove that she will do almost anything to bring a character to life, Blanchett will be seen totally bald in Heaven, her upcoming crime drama in which she stars opposite Giovanni Ribisi. "I had my head completely shaved on camera and that meant no re-takes," she says. "I found that as the days approached to the moment, the tension became ridiculous. I was so relieved when it was over.

"It's like when you're a teenager and just want to go, '[Expletive] it. I'm going to shave my head,'" she adds. "Actually, I shaved the back of my head when I was like 15 and it was great. I think I was trying to be punk, but it was probably a little bit more Cyndi Lauper. But I found it liberating."

Blanchett also found it liberating to play Charlotte Gray — particularly during these uncertain times. "She refuses to let her spirit be defeated by the war, and I've had many, many days since September 11 where I am in absolute despair," she sighs. "You think, 'What can you do?' Charlotte says in the film, 'I want to do something. I've got to get out there. I want to be brave.' She wants to combat her feeling of powerlessness. Now, a few decades later, I find myself dealing with the same challenge."