The film portrays the comic adventures of a group of summertime travellers. Produced at the height of the fascist era, Treno popolare was nonetheless free of propaganda, and featured the first film score by the legendary composer Nino Rota.

A pianist is torn between her quartet's cellist and an exotic Indian maharajah she meets on tour with the troupe. The maharajah, however, has trouble forgetting his dead former love.