Katniss Everdeen is the face of rebellion in "The Hunger Games: Mockinjay - Part 1," and as a new turn for actress Jennifer Lawrence, she's also the voice: Lawrence sings solo and a cappella in this new film.

And just like Katniss Everdeen is reluctant to be a leader, Lawrence was loathe to shoot the scene -- to the degree she called the experience "traumatic and awful."

"I can't stand singing. The idea of singing in front of people is my biggest fear in the entire world. I cried the day that I did that," she told HitFix during press for the film in London this week. "I was shaking. I was like, 'I want my mom.' I've never listened to it. When that scene comes on, I plug my ears."

Lawrence previously sang along to Paul McCartney's "Live and Let Die" in "American Hustle," but this was an altogether a brand new tune, literally and metaphorically. The song Katniss sings is called "The Hanging Tree," an adaptation of lyrics that appear in Suzanne Collins' "Mockingjay" novel, adapted and put to a melody by hit-making band The Lumineers; her "Hunger Games" co-stars urged Lawrence that she did a great job of the scene.

"You should listen to it," said Liam Hemsworth, who plays her longtime District 12 companion Gale.

"You really should, so you can feel better about yourself," Josh Hutcherson (who plays Peeta) added.

The trio's banter was perhaps reflective of the Mockingjay shoots, of what Lawrence called "a very dark movie, very light set."

"I just hate singing. Why can't I just hate it?" Lawrence aimed at her colleagues.

"It's like going back to somewhere where you've had a traumatic experience and you've got to get over it," Hemsworth said.

"Exposure therapy," Huthcherson suggested.

"Thanks, babies," Lawrence shot back, petting Hemsworth's hand.

So don't plan on a J-Law And The Mockingjays album any time soon.

Watch the full interview with Lawrence, Hutcherson and Hemsworth below; their sing-song exchange is above.

"The Hunger Games: Mockingjay - Part 1" will be in theaters on Nov. 21.

After five years as a columnist and editor at Billboard, Katie Hasty joined HitFix in 2009 for music and film reporting out of New York. The Midwest native has worked as a writer, music promoter and in A&R since 1999 and performs with her band Numbers And Letters.