Elsa Brinkmann, an unknown actress from Chicago, is hired by talent agent Bart Langner to star in a film biography of the late, great Hollywood star, Lylah Clare. After reluctantly agreeing to meet the young unknown, Lewis Zarkan, Lylah's director-husband, who has been inactive in films since his wife fell to her death mysteriously on their wedding night, is stunned at Elsa's uncanny resemblance to Lylah. Zarkan agrees to direct the film, and studio head Barney Sheean provides the financing. Although at first resentful of Zarkan's reworking her into an exact duplicate of the legendary Lylah, Elsa is soon drawn into recreating the old star, and even Lylah's personality begins to possess her. Eventually, Zarkan and Elsa become lovers, much to the irritation of Zarkan's housekeeper-confidante, Rossella, a drug-addicted lesbian who had been Lylah's dialogue coach. Once Elsa's transformation into Lylah is complete, she even dares to defy the powerful gossip columnist Molly Luther in a manner that would have done justice to the dead star. Elsa discovers that it is the memory of Lylah that Zarkan truly loves, and she retaliates by flagrantly carrying on a passionate affair with his handsome young gardener, Paolo. Enraged by her infidelity, Zarkan revises the ending of the film and forces Elsa to perform a dangerous stunt on a trapeze, fully aware that Elsa suffers from vertigo, just as Lylah had. As Elsa is overcome by dizziness and plummets to her death, the last moments of Lylah's life are recalled: upon discovering on their wedding night that Lylah was a lesbian, Zarkan had viciously attacked her and then permitted her to fall down a long flight of stairs. Now filled with grief at the loss of the two women he loved but destroyed, Zarkan leaves the successful premiere of his film and returns home, unaware that Rossella is waiting with a loaded gun.