For the sake of interests which unite the aristocratic families of northern Portugal, young Antónia Margarida de Castelo Branco is betrothed to Brás Telles de Meneses, a violent, bohemian spendthrift. Despite the mistreatment and humiliations, the woman is attracted to her husband, who in no time completely dilapidates her dowry. Reduced to poverty, the two live in misery, a situation complicated by the cruelty and madness of Brás, who lets his newborn son die when he refuses to give him the medical care he needs. Distraught, Antónia leaves her husband and seeks refuge in a convent.