Young Peggy Sawyer auditions for a role in the chorus of a new Broadway play, Pretty Girl, at first to be told "Beat it, toots" by the choreographer. After bumping into the director, literally, she gets another shot at showing off her fancy footwork and lands a job in the chorus. The leading lady of the new musical, Dorothy Brock, is a diva actress who got the role because she is the girlfriend of the show's producer, Abner Dillon. When Peggy accidentally bumps into the diva actress on stage during opening night and breaks Dorothy's ankle, she is fired at intermission. Fellow chorus members convince the director that Peggy is the right ingénue to take Dorothy's place so the show can go on. With two days to rehearse, Peggy finds herself on stage in a make-it or break-it career move of her lifetime.
With a spectacular score of hit standards and a chorus line of tap-dancing feet, 42nd Street features such Broadway hits as "Shuffle Off to Buffalo", "We're In the Money", "Lullaby of Broadway", and of course, the title song "42nd Street."