While American Jean Wilson is in a semi-conscious state in a private, London nursing home after the loss of a baby during childbirth, she witnesses singer Jimmy Del Palma remove his wife from the nursing home’s care and hears him accuse the director, Dr. Stepanek, of practicing an outdated form of medicine. After her loss, Jean is emotionally distraught so her husband Tom, who represents U.S. corporations in the British financial world, suggests that she recuperate somewhere in the British countryside. When Jean and her flighty friend, Sybil, go to look for a place to rent, they come upon a particularly grand house, far too big for them, but Jean is drawn to it. Mrs. Burrows, the housekeeper, tells them that the house belongs to Del Palma, whose artist wife Madeleine died recently. Fascinated by stories about Del Palma’s French wife and the contents of the house, Jean rents it, complete with Siamese cat. After Tom and Jean move in, Jean sleeps in Madeleine’s room and “sees” Del Palma carrying his wife up a long flight of stairs. The next day, Jean locates a similar set of stairs, which lead her to an attic studio where she discovers some of Madeleine’s paintings. When Tom returns home that evening he finds Jean sitting in the dark, listening to one of Del Palma’s recordings. Jean tells Tom that she now wants to leave the house as she feels that she is being possessed by the dead woman’s spirit. Tom replies that she needs more rest, but when Sybil invites Jean to see Del Palma perform as the star attraction in a London vaudeville theater, she accepts. Del Palma accompanies himself on the piano as he sings and is obviously appealing to ladies of a certain age. Jean goes backstage to meet Del Palma, but he is slightly drunk and treats her like a doting fan. After Jean decides that Madeleine has returned through her, Sybil arranges for Jean to consult a clairvoyant, Madame Brune, who tells her that Madeleine has found an earthly contact in her. Brune suggests organizing a séance with a medium, to which Del Palma will also be invited. Meanwhile, Tom becomes more and more concerned when Jean informs him that Madeleine has told her that she wants her to replace her. Later, Jean finds a sealed envelope, addressed to Del Palma, in Madeleine’s handwriting, and Madeleine’s Siamese cat finally allows her to pick it up, confirming, in Jean's mind, that she is Madeleine. The séance proves to be a disaster when Del Palma shows up drunk, does not recognize Jean, accuses them all of being charlatans and upends the séance table. However, Jean perseveres and later goes to Del Palma’s hotel. Still treating her like a fan, Del Palma invites her to a nightclub, where they dance, and arrange to meet again. When Del Palma snubs Jean the next day, she delivers his wife’s letter to the theater, but is surprised by the now affable Del Palma, who invites her to a rehearsal of a new song and then to lunch. Meanwhile, Tom again consults with Dr. Stepanek, who tells him that Jean needs psychiatric care. Over lunch, Del Palma tells Jean how much he loved and needed his wife and how he feels responsible for her death, which occurred after he removed her from the nursing home. Del Palma still regards Jean as little more than a celebrity hunter, but when they return to the theater, they kiss and he invites her to join him on a tour of appearances in European capitals, which is to leave that night. Jean agrees and then tells Tom that she is leaving him. Meanwhile, Dave, Del Palma’s manager, finds Madeleine’s letter and gives it to Del Palma who reads it just before going on stage. In the wings, Tom accosts the singer and attempts to explain about Jean’s obsessions, telling him that she is a very sick woman. Del Palma walks on stage in a daze, ignores the audience, and vamps on the piano while he “hears” Madeleine’s voice reading the letter. In it Madeleine explains that she had known for some time, but found it impossible to tell him, that she could not be saved from a fatal illness and would die within four years. She ends it by writing that she does not want him to live alone. Suddenly, Del Palma leaves the stage and the theater and drives to his house, where he tells Jean that he has met with her husband and berates her for prying into his and Madeleine’s lives. Although Jean asserts that Madeleine lives again in her body, Del Palma is outraged by her intrusion into his tragedy and tells her to torment someone else. Jean runs out to a nearby railway track, intending to throw herself in front of a train. Tom and Stepanek, who have just arrived, chase and catch her and, in a cathartic moment, Jean reverts to her old self. Stepanek assures them that now she will recover.