Viviana is a dentist who has been married for years to Mario, a university professor. The couple has not had any children, and she, who has now turned 42, is beginning to despair. One morning, Viviana's car breaks down on the Pan-American Highway. Andrés, who drives a crane, comes to help her and she proposes to have sex just to get pregnant. But soon the relationship between them begins to take on importance. The conflict grows when Monica, Mario's lover, joins the trio and the game of four is discovered. They all end up living under the same roof, until living together becomes untenable.