Jules Francoeur begins as piano tutor to Geneviève Laustin, instructing her from childhood. His commoner status creates a forbidden romance with the bourgeois Geneviève, leading to intense family opposition over class disparity. Their secret relationship culminates in Geneviève's disownment upon discovery.

Transitioning from music teacher, Jules emerges as a key resistance leader against the Prussian invasion and political betrayal. He organizes Parisian commoners against Adolphe Thiers, who conspired to surrender Paris to protect his properties. Jules uncovers this treachery, coordinating efforts to thwart the takeover with strategic insight and commitment to France's liberation.

Despite societal rejection, his bond with Geneviève deepens. They marry immediately after her disownment. Jules sustains a shoulder injury during a duel challenged by Geneviève's former fiancé, Victor Langlois, but survives.

Jules orchestrates intelligence operations against occupying forces, utilizing networks to gather critical information. He arranges for his sister-in-law, Isabelle Laustin, disguised as a boy, to transport vital documents to allies in London, establishing covert communication channels.

During the resistance, Geneviève reveals her pregnancy. Jules faces execution during the suppression of the Paris Commune in the Bloody Week massacre. His death occurs alongside other resistance figures. Geneviève is subsequently shot and killed, resulting in the loss of their unborn child.