Black Swan is about a ballerina named Nina, whose life basically revolves around dance. She lives with her mother Erica who used to be a former ballerina herself. She's very controlling on what Nina does. Leroy is the director of the company that Nina dances at. He's opening a new production called Swan Lake. He was thinking about replacing Beth for this production, and his first choice is Nina. To play the main role on this production you have to be able to play both White and Black Swan. Little did Nina know that she was going to have new competition. Lily, is a new dancer at the company and has also seem to impress Leroy for the spot in Swan Lake. Nina personality perfectly fits White Swan. White Swan is innocent and graceful, as for Black Swan it's guile and sensual which perfectly seems to fit Lily's personality.
Lily and Nina start their rivalry for the spot and as well grow to have a very twisted friendship. Nina's dark ego starts to come out, and starts tormenting her and threatening to destroy her.
Identity Crisis is seen in this movie because Nina starts to lose herself from being a graceful innocent woman to a dark very interesting person. All because of this production and the manipulation and stress that goes on in the company to prepare for this production.