Real estate developer Jake Berman hires private investigator and war veteran Jake Gittes for some run-of-the-mill matrimonial work. After Berman shoots his wife's lover, who happens to be his business partner, Gittes is drawn into a web of conspiracy and deceit involving the oil reserves beneath Los Angeles. While investigating, Gittes hears a voice from his past that causes him to revisit a traumatic case in Chinatown.

Henry Moon is captured for a capital offense by a posse when his horse quits while trying to escape to Mexico. He finds that there is a post-Civil War law in the small town that any single or widowed woman can save him from the gallows by marrying him.