Juan (Fernando Fernán Gómez) no tiene un duro pero vive maravillosamente. Sus noches de juerga y de cabaret son famosas en los ambientes nocturnos de la ciudad. Como heredero de su anciano y riquísimo tío don Patricio, vive subvencionado por sus acreedores a cuenta de la futura herencia. Pero Juan guarda un secreto terrible: hace tiempo que disgustó a su tío y parece que ha sido desheredado. Cuando llega un telegrama anunciando la muerte del tío, Juan regresa a la casa familiar en la Costa Brava para escuchar el testamento. Allí se reencuentra con Ana (Analía Gadé), una hija adoptiva de su tío, que está comprometida con su amigo Andrés (Antonio Ozores) y que podría ser la actual heredera de la fortuna familiar, si se cumplen las exigentes condiciones del testamento.

Juan (Fernando Fernán Gómez) is penniless but lives a life of luxury. His nights of revelry and cabaret are legendary in the city's nightlife. As the heir to his elderly and incredibly wealthy uncle, Don Patricio, he lives off his creditors' subsidies, paid in advance of his future inheritance. But Juan harbors a terrible secret: he has long since displeased his uncle and it seems he has been disinherited. When a telegram arrives announcing his uncle's death, Juan returns to the family home on the Costa Brava to hear the reading of the will. There he is reunited with Ana (Analía Gadé), his uncle's adopted daughter, who is engaged to his friend Andrés (Antonio Ozores) and who could be the rightful heir to the family fortune, if the demanding conditions of the will are met.