Alice, an upper-class Londoner, is recruited into the Special Operations Executive and sent to Paris where she meets Gertrude, an ex-prostitute working for the Resistance Movement. Together they discover that they have a connection to the same man, Ralph D'Olivier, and vow to unravel the mystery of his death.
After narrowly escaping capture by the Germans, Alice is lifted out of France and taken to a hospital for wounded officers where she meets Lil, a working-class northern girl, working as a nurse. Though worlds apart, Alice and Lil form a friendship, and Alice discovers Lil is also linked to Ralph D'Olivier.
Soon, the war irrevocably changes each of these women and they are thrust into a world of heartache and strife beyond anything they have had to endure before. Can they clear Ralph's name and find a lasting love and happiness for themselves?