The story centers around two sisters, Vianne Mauriac and Isabelle Rossingol. Vianne, the older and more responsible of the two is living a peaceful and happy life with her husband and daughter in the French countryside. At the threat of impending war, her life is upended when her husband, Antoine, is sent off the fight for France. As Germany begins to occupy France, Vianne is forced to learn how to survive in these new times and protect her young daughter, Sophie. Meanwhile, Isabelle, the younger more rebellious sister has spent much of her childhood being bounced from one boarding school to the next. After the death of their mother when she was just 4, Isabelle has been largely abandoned by her sister and their father. Neither one knew how to handle the rambunctious girl. As the war starts, Isabelle is not content to sit back and watch as her beloved city of Paris is overtaken by the enemy. Longing to make a difference in the war, Isabelle makes some shocking choices that will forever alter the trajectory of her life.