By Lucy Komisar

Patrick Marber’s After Miss Julie is a psychological thriller, a rich drama that has three characters enmeshed in a web of conflicts that shift the upper hand from one to the other, depending on whether the field of battle is class or sex.

If it’s about class, then Miss Julie (Sienna Miller), the rich daughter of a lord, is on top. If it’s about gender, then it’s John (Jonny Lee Miller, no relation), the lord’s chauffeur-valet. But that holds only if the woman is as neurotic as Julie. Or a woman defeated by her time.

In all its complexity, the story Marber has shaped is enthralling. He’s based it on August Strindberg’s 1888 play Miss Julie, about the daughter of a count, who, bored and stifled by convention, gets involved with her father’s servant. The shifting power relations of their affair sometimes reflects class and sometimes gender.

Instead of the late 1800s at a country estate in Sweden, the action in Marber’s play occurs in 1945 at a manor outside London, the night of the massive Labor Party victory that won 60 percent of the seats in Parliament and broke the power of the conservatives. And while the lord, ironically a Labor peer, is in London at the big celebration, Julie has joined the workers of the estate to toast victory in dance and drink.

The Labor victory, which injects class so boldly into the story, turns out not prevailing enough to challenge all the power relationships in British society.

Under Mark Brokaw’s taught direction, Miss Julie and John, and sometimes Christine (Marin Ireland), the cook and John’s fiancée, stalk and challenge each other around a long wooden table in the serving kitchen. Allen Moyer’s set is back-dropped by a large hutch with plates and glasses. At one side is a black cast iron stove. The stone walls that lead to the servants’ quarters are rough and painted gray and green, to emphasize that there is no elegance there.

Christine seems a tower of strength as John is whip-sawed by the sexually enticing Julie. Her affection towards him is leavened by a very realistic notion of what she can expect from him in their life.

John and Christine of course have voted Labor. He jokes that Churchill is like wine, robust, full bodied and finished. But John doesn’t easily shed the class indoctrination he has imbibed. He criticizes Julie’s behavior to Christine. He says, The rich should never sell themselves cheap; you act common, you become common. Labor won, but these servants remain in their class places. John’s father was a laborer on the estate, his family worked there for generations. Julie jokes that he’s a secret Tory.

John has had a crush on Julie since childhood, and she plays with her power to humiliate him. The election may have liberated classes, but not women. Sexual repression seems to have pushed her around the bend. Her fiancé breaks off their relationship when she plays whip games with him in the stables. The suggestion is that they don’t have sex and her enticement was rather outré. Things won’t get much better with John.

Sienna Miller, thin, soignée, simply but elegantly dressed (costumes by Michael Krass) carries off the role with great aplomb. Sometimes it seems as if she hardly feels the torments we must assume she is going through. Is that a failure of emoting? Or perhaps it is part of upper class sang froid. In the end, it works, because the shifts are a surprise.

I’m just a simple country girl, she tells John and toasts to socialists, to love, to the workers.

He enthuses, The workers! Then she ripostes, Now kiss my shoe as a sign of respect! Is that an upper class act to humiliate him, or is she toying with him as a seductress? He goes to do it, and she kicks her leg aside. Hmmm. Are we throwing class aside for a sado-masochistic game?

Marber cooks the tension to the boiling point.

Johnny Lee Miller at first seems to feel a good deal more than Julie. Or at least to express it. To begin with, he feels his station: A man of my class can rise as far as bread, but not cake. He says she’s patronizing; it’s in her blood. But her attentions seduce him into thinking he can use her to rise. He wants to open a nightclub in New York. He’s smart enough to know they can’t do anything in London. But she informs him blithely that she doesn‘t have money; it’s all in trust.

He’s angry and he jabs, using the gender disguised as class weapon against her: No woman in my class would seduce me like that.

Then Marber suddenly blames feminism! Julie’s mother was for women’s emancipation and wanted her daughter to demonstrate the equality of the sexes. But the lord beat the lady. And the lady hit back! Whew! The family was as dissolute as the class system!

Are we surprised to learn that the lord plays the Labor peer but despises the lower classes?

Sienna Miller is very good (seductive of the audience) as she shifts between the woman empowered and the woman distraught. Her Julie is mean and manipulative, neurotic to point of pure evil. She is powerful in her class, but in the end the weak and the strong shift places. Does gender trump class? Does Marber trump Strindberg?

After Miss Julie. Written by Patrick Marber, Directed by Mark Brokaw. Roundabout Theatre Company. American Airlines Theatre, 227 West 42nd Street. 212-719-1300. Opened October 22, 2009, Closes December 6, 2009.