In the new Western, which opens this week, she's a single pioneer woman in the Nebraska Territory who volunteers for an unsettling and dangerous journey transporting three insane women to Iowa for special care.
In the original novel by Glendon Swarthout, Mary Bee is described as "plain as an old tin pail."
"To me, she's one of the most beautiful people in her spirit," says Swank, who recently visited The City. "She does this not because she wanted to please the other person, but because it was the right thing to do."
She describes her director, Tommy Lee Jones, as "very specific," but also "animated" when discussing the rhythm of a scene.
However, he was not easy on his leading lady, and in one scene she actually eats a handful of grass.
"That was a true gag," she says.
Swank is often viewed as a tough girl, but in real life she doesn't always feel that way. Every role she's ever taken, she says, is scary.
"That's partly why I take them on. Every day I have that fear: am I going to be able to do this today? Is this the right thing for me? Am I following my instinct? I'm trying not to second-guess myself, and also trying not to overthink it. That's what life's about," she says.
One decision she made involved Mary Bee's costume. Swank liked Mary Bee's dress, which had been slightly modified to allow for movement and hard work, but hated her bonnet.
"It had no service whatsoever," she says. "It didn't keep the sun out of your eyes. I'm plowing and I can't see anything. It pressed on your ears. It was strictly a look. And I couldn't wait to get rid of it. It was my idea to lose it on the horse, when I'm galloping away. I'm done with this thing."
Riding horses was also new to Swank, so Jones, brought in experts to teach her.
"He rode with me the first time to see if I could figure it out, or if they were going to have to bring someone else in to be a double. I'm not going to do a boxing movie and do all my own stunts and then have someone ride my horse," she exclaims. "Oh no! I was going to figure it out!"
IF YOU GO
Starring Hilary Swank, Tommy Lee Jones, John Lithgow, Meryl Streep
Written by Tommy Lee Jones, Kieran Fitzgerald, Wesley A. Oliver
Directed by Tommy Lee Jones
Running time 2 hours, 2 minutes