The movie looks at the marquis’s last days, locked up in the madhouse at Charenton. At first, he’s treated royally, surrounded in his cell by his books, drinking fine wine–and writing his pornography on the sly. “He’s like some dreadful old legendary rock star up in the deluxe suite,” says Rush. But a harsh new warden arrives, and the marquis becomes locked in a psychological battle with a cruel oppressor. The complexity of the character is an actor’s banquet: the marquis is brilliant, arrogant, funny, charming, angry, perverted and cruel himself. Rush plays him so subtly and convincingly that talk of another Oscar nomination is already in the air. “The key for a lot of the scenes was seeing when the volcano under the charm emerges,” says the actor. “To see a grown man throwing a major tantrum is, you know, dramatically fascinating.”

It’s been only four years since Rush, now 49, won his first international raves for playing a very different sort of childlike character, the piano prodigy in “Shine.” For the longtime stage actor, it was only his second film, and he won a best-actor Oscar for it. Since then he’s been nominated again for an Academy Award, for his supporting role in “Shakespeare in Love.” Despite his sudden huge success, Rush seems immune to Hollywood’s siren call. He lives in Melbourne with his wife, Jane Menelaus, also an actor (she plays the marquis’s wife in “Quills”), and their two small children. He’s happy to shuttle between film sets and the Australian stage. As he talked about his role in “Quills,” he was still sporting the curly-topped kid’s haircut he’d worn Down Under this fall in a play called “Small Poppies,” in which he played a 5-year-old.

The world tends to think of Australia as a onetime English colony, but Rush doesn’t think of himself as just a stepchild of England’s theatrical tradition. “I’m a Europhile who’s also absorbed a hell of a lot of Americana,” he says. “There’s a certain lineage in American acting that goes back to John Garfield–a raw, emotional truth–a grand tradition of actors that I always love.” Like who? “You know, De Niro, Pacino, Shelley Winters, Rod Steiger,” Rush goes on, pausing for a moment to light a cigarette. “They construct that kind of unpredictability and nuance of character in the jigsaw puzzle of making a movie. I was always in awe of that, particularly when I was working only in theater.” Unpredictability and nuance, of course, is what Rush’s Marquis de Sade is all about. In “Quills” Rush knows how to make all the pieces fit.