It's fitting that Darren Aronofsky had to struggle for years to get Black Swan made. A movie about a ballerina's agonizing quest for perfection might seem a little hollow if it were effortlessly cranked out on the Hollywood assembly line; Black Swan, on the other hand, has the marks of a passion project. You can practically see the metaphorical blood oozing from Aronofsky's swollen directorial feet.

Black Swan is a wholly engrossing, almost unbearably tense drama about a fairly mundane thing: backstage anxiety in the performing arts. Countless movies have addressed the same subject, but I feel safe in saying none have addressed it in quite this way. Aronofsky, working from a screenplay by Mark Heyman and Andres Heinz, shows a knack for combining genres in a most unsettling fashion. Here you'll find psychological thrills, body horror, sexual awakening, symbolic self-discovery, hallucinatory trickery, and the terrifying calf muscles of ballet dancers, all in one movie.

Natalie Portman stars as Nina Sayers, an up-and-coming ballerina who dreams of dancing the lead in Swan Lake. This is a double role, as you are no doubt well aware through your intimate knowledge of Swan Lake, with the same ballerina playing both the Swan Queen and her enchanted look-alike, the Black Swan. The director of Nina's company, a very demanding, very French fellow named Thomas Leroy (Vincent Cassel), is sure Nina has the wholesome grace and technical proficiency to play the White Swan, but he doesn't think she can be wild and passionate enough to pull off the seductive Black Swan. Thomas' vision of the Black Swan calls for a dancer far looser and more sexually charged than the prim, almost virginal Nina.

Nina is alarmed to note that the ideal Black Swan would be the company's newest dancer, Lilly (Mila Kunis), who comes late to rehearsals and smokes cigarettes in the studio, and who tends to dress in black anyway. Nina is also alarmed to note that Lilly looks a lot like her. Then again, as is pointed out by someone later in the film, ballerinas all tend to look alike anyway.

That isn't just a trivial observation, either. Nina's controlling mother (Barbara Hershey), Erica, had to end her own dancing career early and now lives vicariously through her daughter. Beth MacIntyre (Winona Ryder), who used to be Thomas' prima ballerina, is likewise retiring against her will, with Nina replacing her. Nina, Lilly, Erica, and Beth represent different aspects of the female psyche, like one character split into four parts, so it's appropriate that they bear a physical resemblance to one another. Aronofsky frequently exploits this to eerie effect by making us momentarily uncertain which of the other three women is in the room with Nina. Sometimes Nina isn't entirely sure herself.

Speaking of resemblances, Black Swan has some with Aronofsky's previous film, The Wrestler. In particular, both films show in excruciating detail how much physical pain some artists are willing to inflict upon themselves in the pursuit of perfection. Nina is at the start of her career while Randy "The Ram" Robinson was at the end of his -- she is ambitious; he was desperate -- but they share an all-consuming drive to be the best.

Nina is off-balance for most of the film, and we don't know any more about what's happening to her than she does. She has dreams and hallucinations that contribute to her disorientation, but the genuinely bizarre behavior of her mother, her director, and her colleagues adds to it. There seems to be madness around every corner. A sense of dread pervades the film, as if something awful could happen at any moment. The kicker is that since Aronofsky has avoided establishing the film as any particular genre, we never even know what KIND of awfulness we're expecting. It feels just as likely that a dancer will suffer a gruesome natural injury as it is that one will be attacked by her doppelganger.

At the center of this psychological nightmare is Natalie Portman, giving the best performance of her career. (Yes, better than the Star Wars movies.) She's in nearly every frame of the movie, often dancing, often in close-up, conveying a huge range of intense and complicated emotions. No matter how suspenseful, strange, or astonishing things get, we're right there with her, feeling every bit of Nina's fear, confusion, excitement, and eventual liberation.

Portman might be the perfect collaborator for Aronofsky. She tends to come across as intelligent, delicate, and refined, but she's also capable of coarseness. His films can be graphic and harsh, yet beautiful in their way, filled with visual poetry. The actress and director are an especially good fit for Black Swan, which examines the dual nature of man, the good and evil we all have in us.