Arriving in Lisbon from London, Basílio falls in love with his cousin Luísa, but he must go to Brazil, promising he will eventually marry her. As time goes by, he sends her a letter ending the relationship and she marries Jorge, an engineer. One of Jorge's rich aunts dies, leaving him a small fortune and her former maid Juliana. Juliana gets hold of love letters between Luísa and Basílio and starts to blackmail her employer.