Bette Davis stars as aging actress Margo Channing, whose long-successful Broadway career is based upon plays written by Lloyd Richards (Hugh Marlowe) and directed by Bill Sampson (Gary Merrill). Bill is also her lover, although their relationship is stormy due to temperamental Davis' insecurity about their age difference (Bill is eight years younger). (Davis and Merrill wed in real life, later in 1950). Margo's best friend is Lloyd's wife Karen (Celeste Holm).

Karen takes pity on a starstruck young woman who keeps hanging around the theater, hoping to get a glipse of Margo. This lovely, ingratiating young woman is Eve (Anne Baxter) who, upon being introduced to Margo, soon becomes her servant and secretary. Gradually it becomes apparent that Eve wishes to become the next Margo Channing, as she tries to take Margo's place in Lloyd's upcoming play, and even tries to steal both Lloyd and Bill. Eve's rise is partly choreographed by sarcastic, cold-hearted theater critic Addison De Witt (George Sanders). Marilyn Monroe, already stereotyped, has a small supporting role as a dim-witted would-be actress.

The script is about as good as it gets. Margo's line "Fasten your seat belts, it's going to be a bumpy night" is the most famous, but in their context many others are just as good. My favorite is Margo's withering comment "All playrights should be dead for 300 years!" Underpinning the script and story is Margo's fear of losing both Bill and her career to the younger, more attractive Eve, while not realizing that even her spoiled diva personality is superior to Eve's fraudulent humility and cunning manipulations. The awards ceremony shown at film's beginning and end epitomizes Eve's (and the theater's?) phoniness, with Eve in her acceptance speech thanking Margo, Lloyd, Bill, and Karen while they in turn watch her with ironical contempt.