In late 19th-century Lisbon, Carlos da Maia (Graciano Dias), a wealthy, aristocratic doctor raised by his traditional grandfather Afonso (Marcello Urgeghe), immerses himself in the decadent social life of the capital with his friend João da Ega (Pedro Inês). Carlos meets and falls passionately in love with Maria Eduarda (Maria Flor), a striking, sophisticated woman who has recently arrived in Lisbon under the protection of a wealthy benefactor. They begin an intense, hidden romantic affair. However, secrets regarding family origins emerge, revealing that Maria Eduarda is actually Carlos's long-lost sister—a revelation that tests the family legacy and leads toward emotional devastation.