"Dom Casmurro" is a novel by Brazilian author Machado de Assis, published in 1899, and is considered one of the masterpieces of Brazilian literature. Narrated in the first person by Bento Santiago, nicknamed Dom Casmurro, the book tells the story of his life, focusing especially on his love for Capitu, his childhood friend and great passion.

The novel is known for its ambiguous and psychological nature, exploring themes such as jealousy, betrayal, and memory. Throughout the narrative, Bento recounts his relationship with Capitu and the suspicions of betrayal that arise after the birth of his son, whose appearance makes him question his wife's fidelity. Capitu is portrayed as a complex character, with “undertow eyes” that both captivate and unsettle Bento.

The question of Capitu’s possible infidelity is never resolved, leaving the reader in suspense and raising questions about the reliability of Bento's narration. "Dom Casmurro" explores the subjectivity of memory and the influence of jealousy, becoming a profound study of human psychology and the limits of truth. The ambiguous ending makes the book one of the most discussed works in literature, leaving the interpretation open to the reader.