The tragic brilliance of Out of the Past lies in its relentless series of double-crosses. The major twist reveals that Kathie, who initially seduced Jeff into believing she was a victim, has returned to Whit and is actively conspiring to frame Jeff for the murders of Whit's tax attorney, Eels, and Jeff's former partner, Fisher. Kathie's sociopathy reaches its peak when she murders Whit herself, leaving Jeff with a horrifying ultimatum: run away with her and take the blame for the murders, or die.
The climax reveals Jeff's ultimate, fatalistic choice. Realizing that a life with Kathie is a fate worse than death and that he can never return to Ann's pure world, Jeff secretly calls the police to set up a roadblock. As they drive toward it, Kathie realizes the betrayal and shoots Jeff point-blank before being gunned down by the police. Jeff's death is a calculated suicide and an act of moral reclamation; he ensures Kathie can never ruin another life, paying for his past sins with his own. The film ends with The Kid lying to Ann, telling her Jeff was running away with Kathie, thereby breaking Ann's heart to save her future.