Chapter One: The narrative unfolds through the perspective of Jean de Carrouges, portrayed by Matt Damon. Following his service in the Caroline War, Jean and his friend, the squire Jacques Le Gris (played by Adam Driver), swear loyalty to Count Pierre d'Alençon, whose authority is recognized by King Charles VI (as depicted by Alex Lawther). Tensions rise when Jacques reveals that Pierre has ordered his new vassals to contribute to war levies, leading Jean to seek leniency due to his financial struggles. To resolve his monetary issues, Jean marries Marguerite de Thibouville (portrayed by Jodie Comer), receiving a generous dowry and inheriting several valuable estates. However, Pierre has already bestowed one of Jean's inheritance pieces upon Jacques, which sparks a legal dispute. Jean’s pleas for the land are dismissed by the King, and in a twist of fate, Pierre promotes Jacques to captain of a fort historically held by Jean's lineage. Subsequently, Jean's valiant efforts in a Scottish campaign earn him knighthood but leave him in dire financial straits. Upon returning home, Marguerite confides in Jean that Jacques has violated her while she was alone, which propels Jean into a fierce resolve to challenge Jacques to a duel to the death—an appeal granted by King Charles VI.
Chapter Two: As we shift to Jacques's point of view, we discover how he gains Pierre d'Alençon’s (played by Ben Affleck) confidence through his adeptness in managing finances, paving his way into the court’s inner circle. Jacques becomes infatuated with Marguerite, persuaded by her moments of kindness that she may reciprocate his feelings. With Jean away, Jacques manipulates circumstances to find himself alone with Marguerite, using a ruse involving a servant to gain entry to her chambers. He ardently professes his love, but Marguerite, steadfast in her marriage, insists they leave. Defying her wishes, Jacques pursues her into her bedroom, where he forcibly engages with her, believing her compliance to be consensual. After their encounter, he warns Marguerite to keep silent about the event. Later on, word of Jean's accusations against Jacques regarding Marguerite reaches the count, but even as Pierre tries to dismiss the claims, Jean seeks an audience with King Charles and insists on a duel.
Chapter Three: The perspective shifts once more to Lady Marguerite de Thibouville. As her marriage faces trials due to her inability to conceive, Marguerite reveals her true intentions for being kind to Jacques—primarily to secure favor at court. Despite Jean's strict orders to remain in the castle, his mother contravenes them, taking the servants on errands. Jacques seizes this opportunity, once again entering the castle to impose himself on Marguerite. He brazenly declares his affection, ultimately committing a violent act against her. Following her husband’s return, Marguerite discloses the assault, prompting Jean’s mother to pressure her to retract her claims for the family's sake. The tension escalates when Marguerite learns she is pregnant amidst the ongoing trial against Jacques, yet she stands firm in her revelation. King Charles VI permits the duel to proceed. Marguerite is confronted by Jean, who neglects to inform her of the dire consequences she may face if he loses; shortly thereafter, she gives birth just days before the fateful duel. The confrontation escalates to ferocious jousting between Jean and Jacques, eventually transitioning to a gruesome hand-to-hand battle. Jean is wounded but ultimately overpowers Jacques and demands a confession or face condemnation. Jacques maintains his innocence until the bitter end, and Jean, in a moment of triumph, ends Jacques's life. While Jean revels in his victory, Marguerite follows quietly behind, burdened by her ordeal.
In a somber epilogue, we learn that Jean met his end while fighting in the Crusades a few years later. Meanwhile, Marguerite persevered, managing the estate and living a tranquil life for the next thirty years, choosing never to remarry again.
