The story begins with an exchange of letters and news clippings between Alan, a scientist working on parasite eradication in Colombia, and his wife Anne at home in the U.S., concerning an epidemic of organized murder of women by men. Some scientists suspect a biological cause for this sexually selective insanity (selected observations of lab animals indicate that the normal male sexual urges are spiraling out of control, resulting in death), but the murderers feel it is a natural instinct and have constructed elaborate misogynistic rationalizations for it. For example, a new religious movement is spreading along with the murders: the Sons of Adam, who believe that women are evil, that the garden was a paradise before women were introduced, and that God is telling them to get rid of all of the women. When the religion initially arises, prior to the organized murders, little is done to stop the ideology's spread, nor are their actions of evicting women from the areas the men control prevented. Alan realizes that the disease causes male sexual impulses to instead become violent impulses. Alan, a sensitive, kindly man, realizes that he himself is succumbing and tries to resist the impulses, as well as isolate himself from women. While this occurs, his wife and teenaged daughter have a number of mother-daughter conflicts: the daughter, faithful to her father, refuses to believe her mother's warnings about him. She sneaks off to visit her father, and he murders her, killing himself after the horrific realization of his action. Anne flees north, to Canada, since the disease began in the tropical zones and spread outward. After most of the world's women are dead, adult men start murdering boys
