The film portrays a day in the life of the city and the people of Porto, as well as the urban activities that take place daily along the right bank of the Douro River: the circulation, loading and unloading of boats, the river and its ambiance, the bridge, the neighborhoods where the working population lives, who get their food from the river's toil. It seeks to portray all the activity that takes place daily on the banks of the Douro: the Ribeira wharf, the circulation, loading and unloading of boats, the river, the people, the D. Luís Bridge and the surrounding neighborhoods (with emphasis on the Barrio do Barredo), as well as the Foz do Douro Lighthouse and the Codeçal Stairs. The bustle of the riverside area of the city of Porto is illustrated with the river as a central character, as a backdrop. Men, women and children, humble people, stir in confrontation with it, converging into a single identity. The film illustrates a day in the life of the laborious citizens of the city of Oporto, from morning until late at night, in the last years of the 1920s. It portrays the fascination for the splendor of the Douro, the river, and its people of a seductive city. It is the framework suggested at each step, the snapshot. The poet José Régio summarizes the subject of the documentary as follows: "The modern poetry of iron and steel, the charm of nature through its various aspects and nuances, the tone of the hours, the joy and misery of man and animal in the struggle for daily bread, - everything, during a day of activity on the banks of the Douro, is given to us with true greatness.".