In the movie, Nina (Natalie Portman

In the movie, Nina (Natalie Portman) is a highly promising young ballerina, and is the frontrunner to be the new star of the Swan Lake production being staged by a New York City ballet company, in which she needs to embody two diametrically opposite roles - that of the virginal, pure White Swan and the dark, ominous Black Swan who seduces the White Swan's lover and thereby causes her death. The ballet's director Thomas Leroy (Vincent Cassel) feels that Nina is perfect for the White Swan half of the role, but lacks the passion and intensity that the Black Swan role requires. Ultimately, even though Nina repels a sordid sexual advance by Leroy, he picks her for the twin-lead role and tells her that she has to let go her crippling mental inhibitions if she is to convincingly play the darkly sensual and seductive Black Swan with the same effortless grace that she plays the White. In the ultra-competitive world of professional ballet this is the opportunity of a lifetime for Nina, one that every ballerina would kill for, and so Nina does her best to immerse herself in the role and become the Black Swan incarnate.