Police cars race down Sunset Boulevard, a famous street in Los Angeles, where the lifeless body of Joe Gillis is found floating in the swimming pool of a palatial mansion.
Joe Gillis is a struggling screenwriter with a few lackluster credits to his name, down on his luck and unable to find work.
Joe attempts to talk Sheldrake, a powerful producer at Paramount Studio, into buying Bases Loaded, his latest script.
Joe then unsuccessfully attempts to borrow money from his friends and agent.
With no money on hand and his car about to be repossessed, Joe’s only option appears to be leaving the bright lights of Los Angeles for a low-paying newspaper job in Ohio.
Joe escapes the car repo men chasing him across the city, but blows out a tire in front of a ritzy mansion on Sunset Boulevard.
The mansion on Sunset Boulevard is not as deserted as it appeared to be; a woman's voice calls out to Joe, thinking him to be a pet undertaker providing funeral arrangements for her dead pet chimpanzee.
Joe is ushered inside by a mysterious butler, Max.
The house owner, Norma Desmond, is a long-forgotten star of the silent screen.
Norma is intrigued to learn Joe is a writer and invites him to stay and take a look at a lengthy script she has written about Salome.
Norma hopes the script will become the movie that resurrects her acting career.
Joe thinks the script is terrible but opportunistically sweet-talks Norma into hiring him as her editor.
Norma pays Joe's overdue rent without his knowledge and Joe's free will essentially vanishes.
Norma becomes rather obsessed with Joe, showering him with gifts, including a bespoke tuxedo and Vicuna topcoat.
A great December rain leaks through Joe’s room and forces him to relocate to a room in the main house previously used by Norma’s three ex-husbands.
Max reveals that he regularly writes Norma’s fan mail to feed into her illusions of enduring public adoration.
For New Year’s Eye, Norma arranges a grand, private party for her and Joe, where she confesses her love for him.
Joe tries to decline Norma's advances gently, but he comes to accuse her of taking advantage of him.
Norma angrily reacts to Joe's rejection and slaps him.
Max is Norma's ex-husband and willingly returned to her as a servant—life without her was unendurable.
Joe agrees to work on the script with Betty and calls the mansion to let Max know he is moving out.
Joe brutally tells Norma there is no comeback, no script, and no fan letters.
Norma prepares for her comeback with a barrage of intense beauty treatments; in the meantime Joe begins to work secretly with Betty on the screenplay at nights.
Max discovers the studio contacted Norma only because they want to rent her rare luxury car, a 1929 Isotta-Fraschini.
Joe is attracted to Betty but restrains himself, partly because she’s engaged and partly he does not want to abandon his now comfortable life with Norma.
Norma finds the script with Betty's name on it and calls her, telling her that Joe is a user and not a good man.
Norma considers the script for Salome complete and sends it off to Cecil B. DeMille at Paramount Studio.
With this newfound revelation concerning the toxicity of his living situation and Hollywood, Joe prepares to leave Norma and return to Ohio.
Norma has tried to kill herself using Joe's razor, prompting Joe to rush back to the mansion and make love to her as an apology.
Norma is welcomed back by many of the older hands and technicians who worked at Paramount Studio in her heyday.
Joe takes the phone and invites Betty to the mansion to witness this for herself.
Joe flees to another party hosted by his friend, Artie Green, where he encounters the script reader Betty—Artie’s soon-to-be fiance—again.
Betty compliments the thematic potential of a particular scene in one of Joe's stories.
Betty and Artie have become engaged but Betty falls for Joe as they spend time working together.
Joe feigns fulfillment with his life as a gigolo when Betty arrives to upset him and extricate himself from the complicated love triangle.
Max wants to hide these facts from Norma to protect her oblivious, delicate ego.
After one night of writing, a sinister Max approaches Joe and confesses his former status as a respected director who discovered Norma and made her a star.
Joe spots Betty and they briefly swap ideas about the script, but Joe abruptly leaves per Max’s demands.