Director Christian De Chalonge uses a docudrama-styled approach to tell the lonely story of Portugese workers in France. In hopes of avoiding the Army, a boy leaves Portugal bound for Paris to find a job. He meets other Portugese upon his arrival but spends most of his time wandering the streets of Paris when his friend cannot be found. The tedium of the feature overshadows the good intent to bring attention to the plight of immigrant workers struggling to survive in a new country.

The great fadista, Amelia Rodrigues, made her screen debut in Capas Negras, which took its name from the black capes worn by the students in the university city of Coimbra, where the film is set. The action begins in a tavern where a group of former students are reminiscing about their time at the university. One of the students, Jose Duarte then breaks into song, performing an impromptu fado in the local Coimbra style. The tavern owner's niece, the aptly named Maria Lisboa promptly retaliates with a fado of the Lisbon variety. The melodramatic plot then centers on the frustrated romance between these two characters, and the soundtrack is essentially a musical duel between these two different styles of Portugal's national song.