Eva Randers is a divorced librarian with a teenage son. She is approaching her fortieth birthday and to celebrate she asks a female colleague to come to dinner with her. At the restaurant the women order dinner and they are drawn into a lively party going on in the next-door ballroom.
Eva is invited to dance by a man belonging to a group they meet That night she is raped by the stranger. After she recovers from the shock and humiliation, she begins systematically to track down the man. She changes from a blonde to a brunette and creates a new personality for herself.
She follows the man everywhere to his place of work when he is taking out his girlfriends and she even takes up bowling, his favourite sport. Finally she makes up her mind, and goes to his apartment with a gun, ready to take her revenge.