At first Margo Channing (Bette Davis) is amused at the admiration of her fan Eve Harrington (Anne Baxter), but enjoying the attention, hires her as her personal assistant. Margo is a great stage actress and her success blinds her to the fact that Eve us using Margo to advance her own career dreams to become an actress, too. Eve first makes plans for Margo's personal engagements, but always makes herself look like the one who was thoughtful and kind. By winning over Margo's friends, they dismiss Margo's concerns that Eve is up trying to undermine her. Then, Eve works on Margo's professional life, showing manager, directors and playwrights that she is very sharp and a quick study. By the time Margo is trying to get Eve out of her life, she is hired as her understudy for the most important part in a play she has ever had. Now the competition is on to see who is the greater actress and who will fail.