New York socialite Caroline Ferriday has her hands full with her post at the French consulate, but her world is forever changed when Hitler’s army invades Poland in September 1939, with its sights set on France.
An ocean away from Caroline, Kasia Kuzmerick, a Polish teenager, senses her carefree youth disappearing as she is drawn deeper into her role as courier for the underground resistance movement.
For the ambitious young German doctor Herta Oberheuser, an advertisement for a government medical position seems her ticket out of a desolate life. Once hired, though, she finds herself trapped in a male-dominated realm of Nazi secrets and power.
The lives of these women are set on a collision course when Kasia is sent to Ravensbruck, the notorious Nazi concentration camp for women. Their stories cross continents as Caroline and Kasia strive to bring justice to those whom history has forgotten.