In 19th century France, Isabelle Laustin, a 15-year-old noblewoman, debuts in high society at a grand ball in Versailles. However, their idyllic life is disrupted as the French army suffers a defeat at Sedan, compelling Isabelle and her family to abandon their estate for Paris. Here, they immerse themselves in the resistance against the Prussian forces, embracing a new role in the tumultuous events of the era.