Phyllis Dietrichson (Barbara Stanwyck) is the scheming housewife who conspires with insurance agent Walter Neff (Fred MacMurray) to off her husband (Tom Powers) for the insurance payout in film noir classic Double Indemnity (1944).
Neff is immediately dazzled by Dietrichson during a chance visit to her house to inquire about auto insurance renewals for her husband. During a second encounter, he quickly realizes that she is feeling around about the possibility of buying a life insurance policy for her husband, without his knowledge, and shuts it down.
But she has her hooks in him already, as he can't stop thinking about her. When she visits him later, and tells him how desperate she feels in her loveless marriage, he succumbs to temptation and agrees to help her cash in.
A life insurance policy is signed unknowingly by the clueless husband, and then Neff and Dietrichson plan and execute his murder, making it appear to be an accident.
But almost immediately, things start to go awry. Vigilant claims investigator Barton Keyes (Edward G. Robinson) starts smelling something fishy. Neff feels the noose start tightening around him as Keyes starts piecing things together.
Neff eventually discovers that Dietrichson has been seeing another man the whole time, and belatedly realizes that she's been using him, setting him up to take the fall. He confronts Dietrichson at her house, intent to kill his partner in crime to erase any trace of his involvement in the crime. At this last meeting, she shoots him first, mortally wounding him, but at the last moment cannot finish the job. He can and does, however, ending her life with a close-range shot from her own gun, now turned against her.