Ricardo Rodriguez, a second-year medical student at the University of Madrid and Leonor de Sorarrain, the daughter of a Spanish grandee fall passionately in love. After a short courtship the two marry in a grand church wedding.

Ricardo returns to his studies, along with Leonor. She soon becomes pregnant and gives birth to a girl, Theresa. The delivery is uneventful but soon after birth the newborn shows signs of a progressive degenerative disease. By the sixth month baby Theresa expires.

The autopsy reveals astonishing results. A visiting professor diagnoses a rare genetic disease that the couple find difficult to accept. The young couple must decide if they dare having further children, risking the same outcome as baby Theresa.

The visiting professor offers Ricardo and Leonor a possible solution that would require them to follow him to his native country. This journey results in profound lifestyle changes.