The film's narrative is framed by the death of its narrator, Joe Gillis. We see his body in the pool at the very beginning, and the rest of the film is a flashback explaining how he ended up there. The central plot twist is the gradual revelation of the true nature of Norma's world. We learn that all of her fan mail is actually written by Max to maintain her delusion that she is still famous. Max's devotion is further explained when he reveals to Joe that he was not only a prominent director who discovered Norma but also her first husband.
The climax is reached when Norma discovers Joe's secret collaboration and budding romance with Betty Schaefer. Joe, in a moment of brutal honesty, confronts Norma with the truth about her faded stardom and the fake fan letters. As he tries to leave her for good, Norma, unable to handle the destruction of her fantasy world, shoots him multiple times, causing him to fall into the swimming pool. The film's final scene shows Norma completely detached from reality. As the police and news cameras arrive, she believes she is on the set of her comeback film, "Salome," with Cecil B. DeMille directing. She descends her grand staircase, ready for her close-up, a chilling and unforgettable ending that cements her total break from reality.