Pitfall (1948)

John Forbes is a family man who's jaded with his life, routine and job as an insurance adjuster. Life gets a little more exciting for him when he calls upon femme fatale Mona Stevens whose boyfriend has embezzled from a store insured by Forbes' company and showered her with gifts. Forbes finds Mona through MacDonald, a private detective, who freelances for the insurance company. Forbes goes to collect the ill-gotten gifts with the boyfriend in jail and Forbes falls hard for Mona and begins an affair. The problem is that MacDonald has had his eyes on Mona first and is obsessed with her. MacDonald decides to use the soon-to-be-released boyfriend to deal with Forbes and clear the field for himself.