On a September day in Manhattan in 1939, twenty-something Caroline Ferriday is consumed by her efforts to secure the perfect boutonniere for an important French diplomat and resisting the romantic advances of a married actor. Meanwhile across the Atlantic, Kasia Kuzmerick, a Polish Catholic teenager, is nervously anticipating the changes that are sure to come since Germany has declared war on Poland. As tensions rise abroad - and in her personal life - Caroline's interest in aiding the war effort in France grows and she eventually comes to hear about the dire situation at the Ravensbruck all-female concentration camp. At the same time, Kasia's carefree youth is quickly slipping away, only to be replaced by a fervor for the Polish resistance movement. Through Ravensbruck - and the horrific atrocities taking place there told in part by an infamous German surgeon, Herta Oberheuser - the two women's lives will converge in unprecedented ways and a novel of redemption and hope emerges that is breathtaking in scope and depth.