Young American, Claire Hamilton, arrives in Budapest, Hungary to enroll in a prestigious local ballet school. She meets two more Americans there, young Jason Forrest and his enthusiastic old rich uncle, Zio Joshua, who's attending an art auction. After a visit from a strange woman in black and another young man, Claire becomes inexplicably obsessed with Tchaikovsky's famous ballet "Swan Lake" and her personality changes so completely that she starts calling herself Natalie and can't even remember ever meeting Jason. He becomes worried and tries investigating the mysterious man from the school who took Claire in, which puts him in mortal danger. However, nothing can prepare him for what he discovers in the bowels of an old opera house where Claire/Natalie is about to perform Tchaikovsky's spellbinding ballet.