 Marnie Edgar is an ice-cold habitual thief. She uses her looks to gain the confidence of her employers, robs them, and changes her identity. Her only loves are her horse and her mother, although she has problems with the latter relationship. Marnie applies for a job at Mark Rutland s Philadelphia publishing company. Mark recognises her since he is a client of her last employer, but instead of turning her in, he decides to watch her.