From the bridges of Porto to its estuary, two men are paying tribute to the elegant Douro River. Through Luís de Camões and Prince Henry the Navigator, through its Viking ships and dizzying bridges, the Douro is a great witness to the history and culture of Portugal. Jean Rouch and Manoel de Oliveira are walking alongside while reciting a poem written by de Oliveira himself. During their walk, they reflect upon documentary-making, the charm of the river, and what it represents to them.