Beautiful, carefree Hilary O'Neil is devastated when she finds her boyfriend in bed with another woman. She moves out of their apartment and in with her mother, with whom she doesn't really get along. She sees a newspaper advertisement for a live-in female companion to assist someone who is ill. The only requirements are youth and beauty. Intrigued, Hilary goes to the Geddes mansion in San Francisco's elite Nob Hill for an interview.
Several applicants are already there and Hilary is puzzled because they are older and unattractive. Mr. Geddes is seeking a registered nurse to take care of his son during chemotherapy treatments. He realizes that his son placed the ad that Hilary answered and offers her cab fare home. Hilary angrily refuses and begins the long walk down Nob Hill. The Geddes butler chases after her and asks her back for an informal interview with the son.
Victor Geddes is in his late 20's and has battled leukemia for several years, slipping in and out of remission. He has no friends and lives in isolation in a separate wing of his father's mansion. Before his diagnosis he had a girlfriend and was a college athlete. After an awkward conversation, he offers Hilary the job. She accepts but makes it clear that he is to stay out of her bedroom. They are employer and employee, nothing more.
Victor becomes very ill after his chemo treatment. Hilary is in a panic, not knowing what to do for him. Once he is better, she telephones her girlfriend and confesses that she is leaving. Victor overhears and Hilary decides to stay. She is better prepared to handle the next chemo treatment.
In between taking care of Victor, Hilary looks around his living room. There are pictures of him as a child with his now-deceased mother, with his girlfriend, and winning a race in college. Once he became ill, his friends gradually drifted away and his girlfriend left him. He has immersed himself in higher education and is now working on his doctoral dissertation in art history.
Mr. Geddes calls from Japan, where he is on an extended business trip. He knows that Victor hired Hilary instead of a trained nurse and is worried, but Victor assures him he is getting on fine.
Hilary and Victor gradually become friends and she decides he needs to follow a healthier lifestyle. She buys books on nutrition for cancer patients, fills his kitchen with organic fruits and vegetables, and throws away his cigarettes. In return, Victor attempts to teach her about art and famous paintings. Hilary is not much interested.
One day Victor announces that his chemo treatments are over. Hilary questions this and he becomes angry, telling her to call his doctor if she doesn't believe him. He asks her to go away with him for a while. It is years since he has been anywhere. Hilary buys a used Cadillac and they drive to Mendocino, where they rent a beach house. On the way she learns that Victor never learned to drive. She insists on teaching him.
While unpacking, Hilary finds a box filled with vials and syringes. She asks what it is and Victor tells her it is morphine, for pain. He only brought it along in case he needed it. Hilary chooses to believe this. Over the next few weeks, she and Victor visit the local bar, play poker, and make friends. When asked why he is bald, Victor makes up a story about being in a religious group that required him to shave his head. Gradually his hair grows back in and he abandons his bandanna. Sometimes he asks to sleep next to Hilary, not for sex but because he feels alone.
After a while, Hilary says she should leave now that Victor is well. She doesn't feel right about taking a salary. Victor asks her to stay on without salary but offers to teach her about art in return for all she has done for him. She is sensitive about her lack of education and tries to become interested in art, especially the paintings of Klimst. But it is no use and a thread of discontent threatens their idyllic existence.
One night Victor comes to Hilary's bed and they make love. She admits to having fallen in love with him but is uncertain of their future. They visit a maze, where Victor becomes lost and disoriented. Later, when Hilary wants to make love, he rudely refuses. Then she discovers that the morphine he brought is nearly gone. She rummages through the trash and discovers the used syringes and empty vials. Victor admits that he lied when he told her his treatments were over. He had wanted her to see him with hair. Hilary is furious and begins packing. Once again a man she loves has lied to her. After driving into town she telephones Mr. Geddes, who is now back in San Francisco. He has hired detectives to search for Victor. She tells him where to find his son and warns that he is ill again.
The next morning, Mr. Geddes visits the beach house. He tries to take Victor back to resume his treatments, but Victor refuses. He is done with treatments. All he had wanted was to go away with Hilary for the time remaining to him. Mr. Geddes understands this. Finally Victor agrees to leave but on the next day. There is a dance in town that evening and he wants to see Hilary one last time.
After a heartbreaking conversation, she tells him she will never leave him. If he is to die, she will be there when he takes his last breath. Slowly they walk outside and drive away, leaving the house and all its memories behind.