“Black Swan” follows the story of Nina, a ballerina in a New York City ballet company whose life, like all those in… her profession, is completely consumed with dance. When artistic director Thomas Leroy decides to replace prima ballerina Beth MacIntyre for the opening production of their new season, “Swan Lake,” he narrows his choices to Nina and a new dancer, Lily. “Swan Lake” requires a dancer who can play both the White Swan with innocence and grace, and the Black Swan, who represents guile and sensuality. Nina fits the White Swan role perfectly but Lily is the personification of the Black Swan. As the two young dancers expand their rivalry, Nina becomes dangerously more in touch with her dark side.