Jennifer Jason Leigh is fairly sure her profession is dying. “It’s so hard to even read a good script—forget about act in one,” Leigh says in her familiarly husky voice from her home in Los Angeles. “Writers just don’t have the inclination to develop characters anymore. It’s all: ‘And they also own…a mortuary!’ ” She sighs. “I really should have been born in a different time.”

Leigh, 45, is still America’s most fearless female performer. That shouldn’t be such a secret. But it is—even to those who remember her dazzling turns in the ’80s and ’90s: as a brilliantly damaged hooker in Last Exit to Brooklyn (1989), a sharp-tongued Algonquin wit in Mrs. Parker and the Vicious Circle (1994), a cyberterrorist in David Cronenberg’s eXistenZ (1999). After a spell out of the spotlight (“I only work these days if I like the film”), Leigh is back with a vengeance in this fall’s Margot at the Wedding. Her nuanced, naturalistic performance, a Bergmanesque acting tour de force, should finally net her the awards she’s lacked.

“I like things that are very private and real,” she says of her character, Pauline, earthy, impulsive and the catalyst of the film’s drama. Pauline teeters on the edge of a potentially destructive marriage to depressed underachiever Malcolm (Jack Black), a possibility that lures her estranged neurotic sister, Margot (Nicole Kidman), to their family’s Hamptons beach house to wrestle it out. “He has an amazing memory,” Leigh says of her writer-director, Noah Baumbach, whose follow-up to The Squid and the Whale feels even more personal and accomplished—a true breakthrough. “He really understands people. And he has such a knack for finding the oddest and most recognizable raw human behavior. But really fucking funny, too.”

Margot at the Wedding

Leigh also happens to be speaking about her husband. (Baumbach and Leigh wed in 2005.) But with the actor hitting a new high note—warm, full-bodied and fascinatingly conflicted—in an already rich career, it’s hard to interrupt the mutual-admiration loop. “I always knew Jennifer would be able to do it great,” Baumbach says. “But Jennifer can really do anything as far as I’m concerned. Someone told me about a married couple who’d made a movie together, and they stayed in separate houses—almost like an antisex game! Maybe for other people. For us it was very easy to spend the night in the same bed and have breakfast and go to work; she’d go off to makeup and I’d go to the set, and I’d see her show up as an actor and we’d shoot the day and go home again. Kind of like Mister Rogers taking off his shoes and putting on his sweater.”

“I just knew he was going to get something really good out of me,” Leigh says, “because he wasn’t going to stop. It was like an extension of our trust. I loved the intimacy of it.” Any other benefits? “You can rehearse at home! [Laughs] I always had his ear if I needed it. Not that I took terrible advantage of that.” The wink is audible.

Margot at the Wedding opens Nov 16.