Dom Casmurro is the novel in which Bento Santiago, now old, writes his own life, after a house copied from the old one fails to return his youth to him, and along the way he arrives at a doubt: whether Capitu, the childhood neighbor he married, betrayed him with Escobar, his best friend. Published in 1899, it has 148 short chapters, all narrated by him in the first person.
The story begins in November 1857, in a house on Matacavalos Street, in Rio de Janeiro. Bentinho, fifteen years old, overhears from behind a door the dependent José Dias telling his mother, Dona Glória, that the boy is "hanging around in corners" with Capitu, the neighbor girl, who is fourteen. Dona Glória had promised God that her son would become a priest, and she sends him to the seminary. Bentinho and Capitu, who love each other, swear to marry "come what may."
At the seminary, Bentinho meets Escobar, and the way out of the promise comes from a suggestion by the friend: give the Church an orphan ordained in place of the son. Freed from the seminary, Bentinho studies law, returns a bachelor, marries Capitu and has a son, Ezequiel. Escobar drowns, and Bentinho starts to see his dead friend in the boy's face.
Convinced that he was deceived, he prepares a cup of coffee with poison, gives up before his son, separates from Capitu and leaves her in Switzerland. The book shows no scene of betrayal: everything that supports the accusation is Bentinho's own reading, and that is why the novel remains under discussion.