Patricia Arquette, Steve Buscemi

When Nucky Thompson lets a woman enter his world of dirty politics and bootleg hooch, she usually ends up in his bed. Or dead. Or both. Is the Boardwalk Empire crime lord, played by Steve Buscemi, finally ready to move beyond prostitutes, showgirls and helpless hausfraus? He'll give it a shot with Sally Wheet, a no-baloney speakeasy owner from Tampa played by Patricia Arquette, who spent seven seasons — and won an Emmy — as crime-busting psychic Allison DuBois on Medium.

"The women who've been with Nucky so far are desperately needy or in peril or they want something from him — and that's so not Sally," says Arquette over coffee in L.A.'s kitschy-quaint Larchmont Village. "Sally is her own person, a real dame, a businesswoman who can survive in the harshest of swamps. In a way she and Nucky are equals and that" — the actress adds with a laugh — "will be a whole new experience for the guy! Sally can take Nucky or leave him, and he finds that very intriguing."

Nucky first encountered Sally when he ventured down to Florida to expand his booze biz. She'll soon join him in Atlantic City. "Nucky doesn't have to lie and deny when he's with Sally," Arquette says. "They both operate in circles where, at any time, someone close might stab them in the back — literally! — so they find a kind of safety in each other. I don't know that it's necessarily love. Not yet, anyway. But their attraction is definitely primordial and instinctive." Kind of like the alligators whose skulls decorate Sally's bar.

Boardwalk creator Terence Winter says he "really lucked out" landing Arquette. "She's one of those rare, electric talents who can play a woman every bit as tough as the men yet remain feminine and sexy," he notes.

This marks the first teaming for Arquette and Buscemi, though both came out of the indie film scene where they built careers in raw, edgy fare — she with Lost Highway and True Romance, he with Miller's Crossing and Reservoir Dogs. "I don't know how we failed to collide before Boardwalk but I'm sure loving it now!" Arquette says. "Steve is the consummate professional, and I don't mean that in a bullsh--ty way. He is so loving and gentle, so kind to everyone on the set. And so funny! I'm really happy to see him carry a show and finally be celebrated in this way."

Since her run on Medium, Arquette has not been eager to jump into another big, long-term network project. Instead, she's getting back to the low-budge world and is about to star with Michael Imperioli (The Sopranos) in the true-life indie The Wannabes, about a couple who steals from the mob. She's also nearing completion on the unusual Richard Linklater film Boyhood, which she's been shooting for one week a year since 2002. It chronicles the evolution of a small-town Texas boy from age 6 to 18.

"Ethan Hawke and I play the parents and you'll watch all three of us age as the film progresses," says Arquette. "It's been the most beautiful experience. I'll be an emotional wreck when we finish it." To land the part, she had to make a promise to Linklater. "He said, 'You can't do that actress thing and get plastic surgery or do other weird stuff to your face!"

Arquette was totally down with that, not that her concerns have ever been cosmetic. She's got bigger worries in this world. As the cofounder of Give Love (GiveLove.org) a group that develops and promotes eco-sanitation, the actress has made frequent trips to Haiti since the nation was hit by a devastating earthquake in 2010.

"I don't care if sanitation isn't cool and that it's the least glamorous thing," says Arquette. "The lack of it is killing more kids than AIDS, malaria and TB combined, and so far we've helped thousands upon thousands." The divorced mother of two (she split from actor Thomas Jane in 2011) has witnessed some "pretty traumatic things in Haiti to the point where I sometimes question my future. Maybe I'll give up acting some day and devote my life to saving children."

But, for right now, roles like Sally Wheet have her convinced that it's still worth the juggle. "It's important that we keep telling the story of our species," Arquette says. "It's one of the keys to our survival."

Boardwalk Empire airs Sundays at 9/8c on HBO.

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