In Rio de Janeiro, beautiful Rosa dedicates herself to bringing happiness to as many men as possible. Though she lives with one man, hotheaded Lino who owns a coffeeshop, she continuously resists his offers of marriage, claiming that her capacity for love is too great to expend on just one individual. Aside from sharing her charms--with Sergio, a bus driver; Nino, a musician; Basilio, a sculptor; Paolo, a fisherman; a student; and a bookshop owner--she takes an active interest in her lovers' family problems and helps them in domestic and business affairs. Rosa also spends time giving people drug samples for all sorts of ailments, obtaining her medications, some of which are outdated, from a local hospital. One day the jealous Lino flies into a rage because of Rosa's frequent absences and beats her so severely that she requires medical attention at the hospital. The attending doctor attempts to explain to her that love should not be dispensed freely, like inoculations, but should be shared with only one other person. For a brief time Rosa experiments with this new theory but quickly discovers that she has succeeded only in causing quarrels, hurt feelings, and discontent among her friends. Incensed by the poor advice given to her by the doctor, Rosa smashes most of his research equipment and then goes to look up her former male companions and resume her happy and carefree life.