NEW YORK - "Maintaining his dignity through this entire maddening experience": That's how actor Adrien Brody sums up musician-composer Wladyslaw Szpilman's struggle to survive the Warsaw Ghetto, as recounted in his memoir The Pianist. It was also the challenge posed to Brody when he took the role of Szpilman in Roman Polanski's movie - a project all the more charged because Polanski barely escaped the liquidation of the Krakow Ghetto and lost his mother in Auschwitz.

For the 29-year-old actor who was supposed to emerge as a star from Terrence Malick's 1998 The Thin Red Line, only to be cut from most of the picture, The Pianist has become an unexpected career breakthrough, earning him several best actor prizes, most recently from the National Society of Film Critics (which named The Pianist best picture and also honored the direction and the script). But for Brody the big enticement was not the promise of prestige but the chance to follow a master filmmaker into an existential quest.

Speaking for the audience as well as for himself, Brody says, "You concentrate on an individual's loss and isolation, and you can relate much more to this struggle than to a bigger picture. It takes you toward tremendous insights into sadness, suffering, the strength to go on."

Although much of the film plays like a one-man show, and Szpilman maintains a solitary allure even when he's part of the ensemble, Brody says that performing such a distinct, separate character was no luxury. He was conscious that an audience "would have to root for this guy, but he does nothing remarkable, nothing for you to root for. He doesn't save the day, he can't beat up the officer that disrespects his father. But he must still be fascinating."

Alone in demolished Warsaw (reconstructed in Berlin and Belitz, Germany, and on the streets of Warsaw's Praga district), he strove to remain "really succinct and truthful, because when you are completely isolated, it's harder to gauge where you're at. You're reacting to things that you have to torment yourself into believing are happening - and the pressure is on because there's nobody else to cut to."

It was, he says, both "an actor's dream - a month and a half with you and Roman Polanski - and the most excruciating time of your life. It was relentless: You had to stay immersed in this horrible state of mind, because it was too difficult to bounce out of it and then back into it."

Polanski filmed the movie in reverse chronology, starting with Szpilman's urban Robinson Crusoe scenes, then going forward to the past - to the formation and running of the Warsaw Ghetto and to the brief sequence of Szpilman's family life right before the German Occupation.

The 6-foot-1 actor took six weeks to go from 160 to 130 pounds and grow a Father Time beard. He worked on his dialect, studied the piano. Although viewers hear Janusz Olejniczak perform the Chopin on the soundtrack, they see Brody's hands working the keyboards. Polanski insisted that Brody learn the instrument well enough that the director could shoot performance scenes without cutaways. And Brody, who last studied classical piano as a child, says, "It allowed me to connect much more with what makes Szpilman Szpilman - those qualities that are hard to define early on."

Brody describes The Pianist as "a total Method production. They created such a realistic environment that everything felt real. They'd destroy all these buildings and send me out into the rubble. And there I was, 130 pounds, freezing - witnessing all this destruction and crying as I went through it because it was just so powerful and upsetting and impossible to grasp. Yet at the same time I saw the perverse beauty in all of this desolation. You had to jump in and experience all these things, in a really dark place far from everything you've ever experienced. Starving yourself encourages all these thoughts of negativity, degradation, isolation, loneliness."

He doesn't mean that solely in a personal way.

"The homelessness that exists today; the fact that whole nations are starving; the potential for war and conflict and bigotry - all these tragic things that you see somehow appear to have much more depth when you've involved in a project like this."

Brody also felt a rare purification. His emaciation "made me feel extremely Zen. It drained me of my own anxiety, my own whatever-it-is that fuels me. I wasn't happy, but I was clear, and calmer. And a serenity comes through in the character - partly because all I had was music, and it was a wonderful distraction from my solitude.

"I practiced incessantly and embraced it as my friend and lover. Because I had to learn to play the pieces, I understood the relationship between an actual pianist and the work he is playing and his instrument. I wouldn't have had that if I had just been able to make it appear as if I were playing. ... I appreciated the discipline it taught me. It encouraged me to go farther than I ever had to go. That was pretty great."

Still, when the other actors came into the picture, "I really welcomed them because I needed some kind of family somewhere. It was nice."

Then he had to shed the psychological weight. "You appreciate all the things you have again - like being able to eat some bread."

For Brody, there was an overwhelming unity to the production. "I had shot a movie in the winter in New York; then we started The Pianist in Berlin, which extended the winter, and then Warsaw, which extended it again. So it was a very long winter. When spring came, it brought some sanity and safety. Things felt less bleak."

Over the years, Polanski's reputation has evolved from cripplingly precise taskmaster to true actor's director. (Acting more frequently himself on stage and screen in the '80s and '90s may have cemented Polanski's identification with his performers.)

"He was specific," says Brody, "and I know actors sometimes resist specificity. But I also felt he knew the time period and the character better than I did because he is a survivor. I looked to him for insight. I took more from him than he was probably aware of. There's a tone he has, a different way of being, an enthusiasm and a looking for things, and I incorporated them into the character. Then, for the beginning of the film, I became simpler, more restrained, more dignified. Not that he's undignified, but he has a heightened awareness and intensity and passion."

Polanski provided Brody with blessed combinations of empathy and stagecraft.

"I was shooting this scene when I was hiding in the attic, and I hear a piano in the distance, below - and I'm so moved that I close the door and start to cry." The scene wasn't working up to Brody's standards until, after a lunch break, Polanski "made everyone shut up and set the camera. Then he played Moonlight Sonata, from below, downstairs. I sat there, and I breathed, and I waited, and it came, and he rolled. And that's a gift. That's when it feels like the director is working with you - when it feels like magic."

Of course, Brody says, "He also liked torturing me, in a way. I'd be so sickly and dirty that we'd laugh about it. It gave him joy that I was really there for him to do this story."

One film Polanski saw before casting Brody was Barry Levinson's Liberty Heights.

"Barry's far less specific," says Brody, "but equally as encouraging. He gave me such freedom. He wanted me to stop worrying about things. 'Eh, don't worry about it, you don't have to show me you're upset, you look upset. Don't even show me it!' And I'd start to have a conversation, and he'd say, 'Don't even tell me! It's visible! Adrien - you're always upset!' It was really fun direction. It made me lighten up a little, and that's great. Barry would tell us stories and make us all laugh or would laugh hysterically at something I would tell him. He was great to me on that, wonderful."

His collaboration with Malick on The Thin Red Line was more perplexing. "You felt less aware of where you were going. There would be a flock of rare birds overhead, and he'd say, 'Oh look at the birds!' He'd get the director of photography, John Toll, and say, 'John, get the birds, get the birds! Adrien, you hold on a minute now. John, get the birds, don't let the birds get away.' And he'd shoot the birds for half an hour and then get back to your scene."

Brody admits that being cut out of that maddening, sometimes brilliant movie was a "jolting" letdown.

"I didn't know until the last minute - and I'd been doing tons of press. I was in the middle of Barry's film, and it was devastating for me. Acting has been my true love. It's what has prevented me from truly failing in life, because it's given me something to focus on. I never want to jeopardize that; all the things that jeopardize that would jeopardize me."

Now his skin's a little thicker - but not too thick. "If you're an actor," he says, "you can't be too tough, because then you're not going to be sensitive enough to connect." And as Polanski taught him, "Don't complain. It just doesn't go anywhere."