It is the night of the annual banquet thrown by the Sarah Siddons Society, and everybody who is anybody in the world of New York theatre is present. Why, there’s critic Addison DeWitt who can make or break a career with a single well-turned phrase. Playwright Lloyd Richards is there with his wife Karen. Producer Max Fabian is in attendance and—ooh, there’s legendary actress Margo Channing, the Queen of Broadway. And at the center of it all is rising star Eve Harrington, winner of the Sarah Siddons Award. Eve seemed to come out of nowhere, literally turning into a star overnight. How does this kind of magic happen?
Flashback to a year ago, when Margo is starring in Lloyd’s latest play and Karen arrives at the theater only to run right into Eve. Eve’s sincerity in confessing to how she has seen every performance of the play touches the playwright’s life, especially her utter devotion to Margo. Karen takes her backstage to Margo’s dressing room where Eve unfurls a story of growing up in the Midwest, marrying young and losing her husband to the war. Everything changed for her the night she happened to see Margo’s performance one night at a San Francisco theater. When the play moved to New York, she had no choice but to follow.
Eve tags along to the airport where Margo’s boyfriend Bill Sampson is catching a plane to Hollywood to direct a film, endearing herself to the star to the point where Margo decides to allow Eve to move into her guestroom. Once there, Eve proceeds to ingratiate herself into Margo’s life to the point of becoming indispensable as an all-around assistant. Then she goes too far: Eve’s arrangement of a homecoming party for Bill without informing Margo results in quarrels over Margo’s jealousy and self-pity under the influence.
Max has set up an audition for Addison’s very hot date to the party, but again things go off the rails when Margo learns that the Eve read with the hottie and turned out to be a very impressive actress herself. Margo gets it in her head that Bill has been secretly audition with Eve…who just so happen to also be Margo’s understudy for the play she’s starring in. Things are about to get worse: Karen decides that Margo’s going off the rails is just her being temperament and acting like a diva and therefore needs to be taught a lesson. The lesson will involve getting Margo out of the way long enough for Eve to have to take to the stage in her place in her role as understudy.
Addison and several other top critics have been invited to attend the performance and watch in admiration as Eve performs like a pro. Addison eavesdrops on Eve’s failed attempt at seducing Bill in the dressing room after the play ends. When Bill leaves, he enters and offers the assistance of his considerable influence to help her star rise. The next day his column not only praises Eve’s performance, but does so at the expense of Margo who personifies his caustic commentary about older actresses trying to play younger roles.
Lloyd decides that he wants his next play to head into production immediately with Eve in the lead role rather than waiting for Margo to end her current run. Bill and Margo announce their engagement and Eve threatens to expose Karen’s “lesson” to Margo through Addison’s column if Karen doesn’t get Lloyd to cast her in his new play. When Karen heads back to the table, she hears Margo saying she doesn’t want to play the part.
When Lloyd’s new play open in New Haven, Eve informs Addison that the playwright is leaving Karen to marry her. Addison tells her that isn’t going to happen since he has learned her past is not the innocent tale he has told everyone, but is rather a story filled with scandal. He also lets her know that Karen told him all about her blackmail attempt before finally informing her that she belongs to him.
Back in the present day, Eve is accepting her award and giving a speech overflowing with seemingly sincere humility. She makes the promises that she will return to the theater after completing the film she has signed to make. Exhausted and depressed, Eve returns along to her apartment only to find a young woman named Phoebe waiting for her. Eve learns that Phoebe is the head of her fan club and just wanted desperately to meet her idol in the flesh. The doorbell rings and Eve—too tired and down to deal with anything—ask Phoebe to take care of whoever it is. It turns out to be Addison with the award she left behind in the taxi. Phoebe takes it from him and lies to Eve by saying it was only the cabbie and not Addison. When Eve is near to collapsing in another room, Phoebe takes the award into the bedroom, tries on Eve’s expensive cape and stands before a mirror practicing posing and bowing as if she had won the trophy.
