The story focuses on Madame Souza, an elderly Portuguese emigrant woman raising her grandson Champion.

Seeking to pull him out of his funk, she buys the child a tricycle, and as the years pass he achieves such excellence as a cyclist that he enters the Tour de France. Unfortunately he and two other riders are kidnapped and brought to a fictional metropolis called Belleville (the inhabitants of Belleville represent caricatured 1950s-era American stereotypes, but the city itself is portrayed between Paris, Montreal and New York City) where a member of the French Mafia forces them to pedal all day on a bicycle-based gambling machine located in the bowels of the Belleville French Wine Center. With the aid of the family dog Bruno, Madame Souza sets off on a paddle boat journey to the city of Belleville. There she meets the Triplettes, now aged and decrepit but still performing, and the four women set out to rescue Madame Souza's grandson.