High school students are gathered in the auditorium to hear a speech given by Alison Gertz. She is an attractive, well-dressed young woman who has AIDS. Her story unfolds in flashbacks.
Only a few years ago, she was a high school student herself. Her wealthy parents, Jerry and Carol Gertz, live in New York City's upper east side. Carol prided herself on being a modern mother. When Alison was a teenager she decided to have sex with her boyfriend. Carol took her to a doctor who prescribed birth control pills.
Alison contracted AIDS when she had sex with a young bartender to whom she was attracted. She knew very little about him, but her parents were out of town and she invited him to her home. They were only together that one time and she never saw him again. For several years she had no symptoms. She finished college, moved into her own apartment, and became a designer. She also acquired a serious boyfriend, Mark, who was getting ready to open a restaurant.
While spending the weekend at her parents' summer home, Alison falls ill with what she assumes is the flu. Her mother calls a doctor, who confirms that it is probably flu. After a few days, Alison is well enough to return to the city. She and Mark visit his restaurant to check on how the work is going. Their friends are getting married and Alison is very happy for them. But her flu-like symptoms persist and eventually she is hospitalized. When asked if she has ever used drugs, Alison discloses that she experimented in college but only a couple of times. That comes back to haunt her.
Test after test is performed but her illness remains a mystery. Mark visits her and so do her parents and her best friend Tracy. Some days she is better but then the fever returns and she has trouble breathing.
Then the doctor breaks the news that she has pneumonia caused by the AIDS virus. He did not think to test her earlier because she did not fit the profile. Alison, her parents, and Mark are all stunned. He will need to be tested as well as everyone she has ever had sex with. The doctor gives Alison some pamphlets and recommends an AIDS support group. In an instant her life is shattered.
Back home, Alison's father is angry because after revealing her college drug use, the insurance company is denying her claim. The doctor who took her medical history wrote down that she was a habitual drug user. Eventually it is straightened out but relations between Alison and her parents are strained. She returns to her apartment and begins contacting her previous boyfriends. They are tested and come up negative. She can't understand who gave her the AIDS virus. Then she remembers the bartender. A friend who is gay reveals that the bartender died of AIDS several years earlier.
Mark's test is negative. He and Alison celebrate by spending the night together. He wears a condom. Later that night, Alison wakes up and finds him in the bathroom, vigorously scrubbing himself with a washcloth. She realizes it is over between them; that he can't deal with her condition. He admits this is true and they part. Much later, she goes by the building where he was going to open a restaurant, only to find it boarded up and a "for rent" sign on the door.
Alison's girlfriends seem supportive. But when she is again very ill and in the hospital, Tracy comes by with a stuffed animal which she places just inside the door of Alison's room. She is too frightened to come in.
The AIDS wing is full and Alison is in a regular room. The nurses wear masks and gloves to tend her, and otherwise they ignore her. Carol is infuriated when they refuse to change the towels placed around Alison to absorb heavy sweating. She charges over to the microwave at the nurses' station to dry the towels herself. The nurses are very upset that she used their microwave. At that point, Carol demands that a room be found for Alison on the AIDS wing.
Alison's fever breaks and she wakes up in a pleasant, cheerful room. The nurse who comes in tells Alison that all the medical personnel on the floor are there because they want to be. Quite a change from the rest of the hospital. Alison makes a new friend, a young man with AIDS, and is upset when he later dies.
Alison visits the support group but is put off by the cigarette smoke and dreary atmosphere. Once again she tries to resume her life. At her friends' insistence, she goes to a party and meets a young man. When he seems interested in her, she blurts out that she has AIDS. To her surprise, he doesn't mind and they began seeing each other. But when she tries to kiss him, he backs away. He didn't realize Alison was falling for him, he thought they were just friends. In a fury she throws him out of her apartment.
She tries to reconnect with Tracy but without success. Then she goes to another support group and this time finds a home. It is for anyone with a life-threatening illness. After sharing her story, she begins to make friends. Her parents come with her although they are clearly uncomfortable. The facilitator suggests that she speak to students at the high school, to encourage them not to have unprotected sex.
After Alison finishes her speech, the room is silent. Then the students give her a standing ovation. Many come up to hug her and thank her.
The movie ends with a message that Alison died in 1992, at age 26.