Mary J. Blige spends much of Dee Rees’ southern tragedy Mudbound holding her tongue. As Florence Jackson, the matriarch of a sharecropper family continually bossed around by the white folks who own their land, she’s swollen with words she’s not allowed to say, starting with “No” to the McAllan jerk who’s always interrupting her dinners to demand that she, or her husband, or her children, obey his commands.

“She’s an observer,” says Rees. “She sees everything, but she’ll say only a little of what she sees.” Instead, Blige channels Florence’s exasperation through her mighty silence. Though during one take, as Jason Clarke’s irritating Henry McAllan once more knocks on their door, Blige couldn’t resist muttering, “What he want?” Rees liked the ad-lib so much she kept it in the film.

At first, Blige’s ability to make an emotional symphony from silence seems ironic to audiences who know her as the R&B queen with nine Grammys, 33 hit singles and over 50 million albums sold worldwide. She’s famous for expressing everything; her grief, her insecurities, her hopes. This summer, she spent her Strength of a Woman tour—her first major string of concerts since divorcing her husband of 12 years—letting her broken heart bleed across the stage, sometimes until she fell to the ground.

“It’s like a therapy session,” says Rees, who saw Blige perform at Madison Square Garden. “She’s not just singing lines at you. She’s reliving every joy, she’s reliving every pain. She makes you feel. I knew she could do it in a more intimate setting.”

“I think my mission is to make people feel and see and deal and heal,” says Blige. Which is why she immediately said yes to Rees when she read Mudbound’s script. Working with the vibrant writer-director of Pariah and Bessie, the biopic of singer Bessie Smith that scored Queen Latifah a Best Actress Emmy nomination? Says Blige, “I was like, ‘It’s a no-brainer, period.’”

Acting is the other way Blige expresses herself, which to her, in a way, means expressing other people’s selves too. “I let people see me coming through some of the most terrible things in public, because I find out that a lot of people are suffering just as bad.” Through Florence, viewers can connect to her character’s fears, especially for her oldest son Ronsel (Jason Mitchell), a WWII soldier, who has to fight racism in Germany and back home in Mississippi. When he heads off to war, Blige can’t watch him leave—a superstition Rees’ grandmother shared that she wrote into the script—and as he rides away, she grabs her stomach, an unconscious reaction that she also does in concert. But Florence’s resilience and wisdom and determination seem to ripple off the screen in 3D. When she smiles, we smile. The details are specific, but the feelings are universal.

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“Dee’s films are like my music,” says Blige. “People watching this film are bawling because of the direction she chose, and the colors; it’s so rich and thick and layered.”

Blige is known for her glamour: the blonde hair, the long nails, the glamorous diva costumes. Rees asked her to pack all that away, even the false eyelashes Blige has worn for decades. Blige, who vibrates with emotion, sobbed when she got rid of her wigs, and teared up when she saw Florence’s flat, ugly shoes. The Queen was stripped bare. She cried on the first day on set. “And then, I was like, ‘Mary you’ve been super dependent on material things that deem you as nice-looking,’” says Blige. “I said, ‘I gotta get rid of Mary—she’s just too vain.’”

On the second day, Blige surrendered. Soon, she was running around set in 100 degree Louisiana heat with her natural hair. Says Blige, “I can’t even describe how liberating it was.” She was forced to file for divorce during the month of the shoot. “I think I was probably at the lowest of my own personal life,” Blige admits. Yet, in a way, she was free.

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“It’s like Mary’s gone, Florence is there and she’s just pouring everything into this character,” adds Rees. “That was a huge trust fall because she’s an icon, she has a brand, she has an image.” During filming, Rees called her actors by their character’s names. One day, she slipped and said, “Mary.” A supporting actor flipped out. “Wait a minute! You’re Mary?” he yelped. He hadn’t realized who he’d been sitting next to in their scene.

Rees succeeded in building a safe atmosphere for her cast to navigate horrible traumas. Blige glows as she describes “this humble, assertive, team player. She’s the director, but she wants to hear how you feel.” The singer-turned-actress has been getting the bulk of awards attention, yet her hushed performance commands attention because Rees forces it to, hiding her star in the back of scenes until the audience begs for Blige to come in focus. “Miss Dee,” says Blige. “You’re director of the year—you’re director of the century.”

Before they started filming, Rees had the ensemble pair off for practice exercises where her characters would face each other and acknowledge their unspoken dynamic. With her onscreen son Mitchell, Blige repeated variations of “You’re making a mistake” as he tried to deny it with varying certainty. With Carey Mulligan, McAllan’s overwhelmed wife, they bounced the lines, “You have the power,” “No, you have the power.” And with Rob Morgan, Florence’s husband Hap, the fictional couple built a romance, telling each other what they liked about their faces.

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“It’s like seed planting,” says Blige of Rees’ strategy. “When it was time for it to surface, it surfaced.”

Blige admits she was “1 million percent nervous,” to tackle the part. But when everyone was assembled on Mudbound’s dirty, sticky, bug-buzzing set, Rees realized she hadn’t just hired an icon—she’d hired a leader.

Laughs Rees, “If someone as huge as her is staying in it and not complaining about mosquito bites then no one else is complaining about mosquito bites.”

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Blige didn’t complain even when she had to confront another phobia: live chickens, which Florence grabs and kills with her bare hands.

“I never told you this story,” confesses Blige, turning to Rees. “When I was a little kid, my grandmother killed a chicken and his head came off and he was flipping and running after me. I was traumatized. So when I saw the chicken, I was like, ‘Oh my god, really?’ Everything that I was afraid of, this movie made me face it.”

“I didn’t know!” exclaims Rees. “But you went through it!”

“Listen, I had no choice,” smiles Blige. “I was like, ‘I’m not going to come here and chicken out over a chicken.’” Blige handled it like Florence would have. She kept her feelings inside and got the job done.

This feature is part of a series of three cover stories celebrating Women in Hollywood for the 12/13 print edition of Deadline’s AwardsLine magazine. Click here to read our feature with Patty Jenkins & Gal Gadot on Wonder Woman, and look out for Greta Gerwig & Saoirse Ronan for Lady Bird later today.