Ultimately Walter Neff betrays his superior, Barton Keys. Keys thinks very highly of Neff and believes he has what it takes to become a great investigator for the insurance company. Neff is an insurance salesman who regularly schedules house calls and doesn't like the idea of working in the office. During one of his outings he meets a overly flirtatious married woman, Phyllis Dietrichson, who has her own secret motives and murderous past.
Phyllis