Jane Langley drives to San Francisco Hospital on a rainy night while she is in labor. Jane uses a pseudonym at the hospital, and surgeon Dr. Fredericks is called from his sleep to perform a cesarean section on her. Before the surgery, Fredericks advises Jane that if she survives, her baby will die, and vice versa. Jane, having left a letter of instruction in the event of her death, insists that her baby's life is more important than her own. As she is wheeled into surgery, Jane recalls the past few years of her life: Jane, a Los Angeles dress designer who reared her younger sister Nancy after their mother died in childbirth, is in love with Bill Prentice, who works in the advertising department of her firm. However, Bill is in love with Nancy, a model for the company. Still stinging from a recent failed affair, Nancy selfishly accepts Bill's marriage proposal, and Jane grapples with her own disappointment. Although bored by married life, Nancy becomes jealous of her sister after she is promoted and starts working closely with Bill. To save her marriage, Nancy fulfills Bill's desire to become a father, but then refuses to share her daughter Deborah with her husband. As time passes, Nancy grows more possessive and vindictive, and shuts Jane out of her life completely. During a consultation with her family physician, Dr. Winston, Jane learns that the Langley women are predisposed to difficult childbirths, and she is advised never to have children. After a few years, Nancy is so bored and bitter that she threatens Bill with divorce, and plans to take custody of Deborah. One day, when Nancy is out of town, Bill encounters Jane at a restaurant, and the two lonely people finally confess their love for each other. Jane nevertheless urges him to stay with Nancy for Deborah's sake, and spends the night on his couch because the hour has gotten so late. When Nancy arrives home in the morning, she assumes they have had an affair and becomes hysterical. Jane is so distraught that she is blinded by tears, and accidentally kills her niece with her car. Nancy and Bill divorce, and Jane becomes estranged from her sister. However, after working closely with a psychiatrist, Nancy finally reconciles with Jane, who believes that another child would restore Nancy's spirit. Jane proposes to Bill and they cross the border into Mexico to marry immediately. A few blissful weeks later, Jane leaves Bill without explanation and drives to San Francisco, all the while praying to have a girl "for them." Back in the hospital, Jane's baby girl is delivered by cesarean section, and as Jane is dying, Fredericks sends for Bill and Nancy. On her deathbed, Jane gives her baby to Nancy, thereby effecting a reunion between the couple.