It all begins when Lucien Lachenay (André Dussollier), famous builder of the moving sidewalk for the 1900 Universal Exhibition, saves the life of the beautiful Alice Avellano (Kristin Scott Thomas), whom her husband, who has gone mad, was trying to strangle. Lucien Lachenay is himself threatened by a group of anarchists who have instructed a young worker, Alphonse (Benno Fürmann), to suppress him. Alphonse messes up the job, but Lucien, impressed by his inexhaustible energy and thirst for knowledge, agrees to be his mentor instead of handing him over to the police. In the years that follow, Lucien, Alphonse, Alice and the young and attractive Laure (Isabelle Carré) will face the game of rivalry, betrayal and reconciliation.