This musical is about show business, and the characters are typical of Broadway's glitter without being types. What is it that we're living for?", sing the impoverished "gypsies", the Broadway dancers, in Act 1 - and the answer? - "Applause, Applause". These lyrics state simply the motive of all the characters in the play; and this song is repeated periodically to remind us of the theme of the show.
As the "Overture" ends, Margo Channing (Lauren Bacall) presents the Tony Award to Eve (Penny Fuller), who graciously thanks "my producer, my director, my writer and above all, Margo Channing." We hear Margo's thoughts as she remembers her opening night a year-and a-half before, when Eve entered her life, and, as the scene changes and we flash back to that night, Margo's admirers crowd her dressing room and fill the air with "Backstage Babble." As soon as Margo can be alone with Bill Sampson, her director and fiancé, she tries to convince him to stay with her and not go to Rome to direct a movie. Bill firmly but lovingly tells her goodbye in "Think How It's Gonna Be." Margo dreads facing the opening night party alone, yet she feels stimulated – "But Alive" – and persuades, Duane (Lee Roy Reams), her gay hairdresser, to take her and Eve to a gay discothèque in Greenwich Village. The lively evening ends back at Margo's apartment. Eve sums up her feelings in "The Best Night of My Life." Margo, seeing her 19-year-old self on the late show, satirically asks "Who's That Girl?"
Four months later Eve has become Margo's indispensable Girl Friday, impressing Margo's close friends, including her producer, Howard Benedict (Robert Mandan). Howard takes Eve to a "gypsy" hangout. "Gypsy," Howard explains,"is the name dancers affectionately give themselves as they go camping from show to show." Led by Bonnie (Bonnie Franklin), the "gypsies" celebrate "the sound that says love" – "Applause." At three a.m. that night after a phone call from Bill in Rome, Margo longingly wishes he would "Hurry Back." Bill arranges to hurry back two weeks later, and at Margo's welcome home party for him a misunderstanding leads to a disastrous evening: "Fasten Your Seat Belts." By this time Eve has contrived to get herself hired as Margo's understudy. Margo, feeling betrayed and threatened, faces Eve with the ironic "Welcome to the Theatre." Bill accuses her of being paranoiac about Eve, and after a bitter fight, he says a final goodbye. Margo is left alone on an empty stage as the curtain comes down on Act I.
Act II opens in the Connecticut home of Margo's playwright friend, Buzz Richards (Brandon Maggart), and his wife, Karen (Ann Williams). Karen, thinking Margo behaved terribly to them and unfairly to Eve, arranges for Margo to miss a performance by draining the car's gas tank. Stuck in the country for the night, they express their warm feelings as "Good Friends." Back in New York, Eve gives a triumphant performance in Margo's role. Howard again takes Eve to the "gypsy" hangout where she snubs Bonnie and her friends, who do a scathing parody of a girl who becomes an overnight star – "She's No Longer a Gypsy."
Margo is devastated by reading a nasty interview that Eve has given, referring to "aging stars." Bill now realizes what Eve's true intentions are and rushes back full of love for Margo, telling her she's "One of a Kind." But the reconciliation doesn't take. Margo is still married to her career. Eve, who has made an unsuccessful pass at Bill, has ensnared the playwright, Buzz. Alone, she triumphantly recalls "One Hallowe'en." But her plans with Buzz are crushed by Howard who claims her for himself, telling her "We both know what you want and you know I'm the one who can get it for you."
Margo seems to have lost everything because of Eve, but suddenly she realizes she could be the winner and she now has a chance at "Something Greater." This means a life with Bill. In the finale, she and Bill join with everybody answering the question "why do we live this crazy life?" – "Applause."