Margaret (Maddie) is the motorcycle-riding Mancunian granddaughter of Russian immigrants. Julia is the daughter of a Scottish lord, educated in Switzerland. Under normal circumstances, they may never have met. But when World War II creates new opportunities for women, they find that their skills can be put to uses that result in their worlds colliding, and a friendship forming. Maddie, handy with machines, discovers the thrills of aviation; Julia, gifted with languages, rises to an unusual challenge and learns she also has a gift for deception.