At the height of the London Blitz, young Charlotte Gray leaves her native town of St. Andrews, Scotland, for bombed-out London; she's not quite sure what she's going to do once she gets there, but she knows she must do something. En route, Charlotte meets Richard Cannerley, a civil servant who notices that she's reading Stendhal in the original French and urges her to contact him once she's settled. He also invites her to a party, where Charlotte meets Peter Gregory, an RAF pilot on leave. After a few idyllic nights in each other's arms, Peter breaks the inevitable bad news: He's leaving the following day for a hush-hush mission somewhere over France. Inspired by Peter's bravery, Charlotte calls on Cannerley and soon finds herself training to serve as a courier for the SOE, a top-secret organization involved in covert operations and sabotage. Charlotte's determination to serve as an undercover operative in France is only strengthened by the news that Peter's plane has vanished somewhere over the Free Zone. And so blond Charlotte is transformed into a dark-haired Frenchwoman named Dominique, and dropped into the picturesque village of Lezignac, deep in heart of Vichy France. There she's met by members of a local communist Resistance network, including handsome architect and head of the resistance group Julien Levade. He puts "Dominique" to work in the decaying chateau owned by his gruff father who hides two jewish boys whose parents have been captured by nazi troops.
While trying to find Peter, Charlotte more and more finds herself attracted to Julien. In order to maintain her cover and protect Julien, his father, and the boys, Charlotte finds herself drawn into a relationship with Rench, a busybody schoolteacher who is collaborationg with the occupation troops.