Though you wouldn't know it by gazing into her huge, almond-shaped eyes and classically beautiful visage, Mary Elizabeth Mastrantonio is one tough cookie.

The star of "The Color of Money," "The Abyss" and now "Class Action" has never played the Hollywood game. She prefers theater over film, nixes all nude scenes and keeps her distance by residing with director-husband Pat ("Cal") O'Connor in London."I can be vicious if I'm not getting what I need," she says without a hint of viciousness. "I have quite a sting."

It comes as little surprise, then, that Mastrantonio will next be seen as a very different - very un-maiden-like - Maid Marian in "Robin Hood: Prince of Thieves," starring Kevin Costner as the bandit of Sherwood Forest and due out this summer. Mastrantonio, in town to hype 20th Century Fox's courtroom drama "Class Action," describes her Marian as a woman who "rolls up her sleeves and isn't afraid to get her hands dirty."

We're definitely not talking Olivia de Havilland here, or even the more spirited Audrey Hepburn of "Robin and Marian."

In "Class Action," Mastrantonio plays a young San Francisco lawyer whose ambitions bring her dangerously close to disbarment. Gene Hackman, a longtime role model, plays her estranged father, also a lawyer. They vent their resentments in court, arguing opposites sides of an auto-negligence suit.

Mastrantonio says she's happy about her work in the $50 million "Robin Hood," even if she spent much of the shoot dodging broadswords. Still, she's concerned director Kevin Reynolds didn't go far enough in debunking the old swashbuckler myths. She fears "contradictions in my character . . . I thought Marian would be more realistic, lustier."

"Class Action" could also have used a bit more starch, in her estimation. "A lot that was taken out (in the editing room) were my reasons for doing the film," she says.

Such candor is refreshing. In this town, it's amazing. But the actress doesn't stop here.

"I'm not a studio baby," she wants all to know. "I know I'm not the first person on every casting agent's list. I don't live here. I don't choose to. I'm torn between loving this business and hating it. Maybe that will change in five or six years, if I find I can't get a job. But frankly, I don't trust them. If you give an inch, they do in fact take a mile. I don't know how much I can give."

As it stands, Mastrantonio, 32, is in no danger of being forgotten by the industry she views as a mixed blessing. She's a triple threat, moving easily from New York stage productions (last summer's "Twelfth Night" with Jeff Goldblum and Michelle Pfeiffer) to prestige TV productions (PBS's recent "Uncle Vanya" ensemble, which she calls "a slice of heaven") to splashy Hollywood fare. In terms of versatility, she almost rivals Glenn Close.

Mastrantonio says she took "Class Action" for the opportunity to work beside Hackman and British director Michael Apted ("Coal Miner's Daughter"). Also, she found herself identifying with the Maggie Ward character, who's caught up in a love-hate thing with her famous lawyer-father. "She goes through so much of what every woman goes through. There's that struggle to arrive, but once you arrive, you question whether it was all worth it. In Maggie's situation, she has two choices: She can go mad or change her course. A big part of it is coming to terms with this man, her father. He's all she has left in the world."

The thing that annoys Mastrantonio most about movie sets: the game-playing, the coy one-upmanship. She can't stand directors who "give you notes on your character even before you've seen the script." Even worse: directors who, for the sake of on-screen conflict, play one insecure actor against another. "I hate directors who go up to an actor and whisper in their ear and then tell you, `I told him a secret about how we're going to play the next scene.' Preposterous!"

That's why working with Hackman was such a treat. "We didn't have to discuss things. We just launched into the script. You don't think about motivation with Gene. You just start in. It was sort of like, `I'll trust you if you trust me."'

As for "Class Action" being too tame and old-fashioned for the savvy "L.A. Law" set, Mastrantonio insists, "I see it as being about two people who just happen to be lawyers. It's not really about the law, per se."

The project also meant an opportunity to "dress pretty" and wash off residual brine from the deep-sea thriller "The Abyss." At the time of that film's release, in fall '89, the actress went on record as condemning director-writer James Cameron's methods. "It's only a movie," she said at the time. "It's not healthy to put people under the gun for that long. The thinking here (in Hollywood) is that the ends always justify the means. I absolutely disagree with that thinking."

Has the actress changed her mind about this?

Of course not.

"See, I don't believe the show must go on. I think if people are in pain and fatigue, as we were, everyone should break for a nap."

Laughing, she adds, "Of course, with that attitude I'll never have my own studio; I'll never be an executive in charge of production. I'm not of that mind, that the show must absolutely go on. Come on, that's ridiculous. Especially now, when people are dying every day in the Middle East."

Next up for this spirited attorney-aquanaut-Maid Marian: "I'm in the middle of fixing up the house (in London). That's what I'll be doing for the next couple of months."