Nina Sayers (Natalie Portman) is a dancer in a metropolitan ballet company. After years of dedicated performances in supporting roles, she is finally given her shot when she is cast as the lead in a new production of Swan Lake. Her director (Vincent Cassel) believes that, whilst she can embody the virginal innocence of the White Swan, she lacks the pulsing sexuality to convincingly play the evil Black Swan. Nina becomes obsessed with her dual roles, and as she starts to believe that a younger, less skilled but more sensual dancer (Mila Kunis) is out to steal the part from her, she descends into a paranoiac frenzy.