This is an engaging novel that blends historical fiction with a mystery and character studies. The history of the undercover work that the girls did to help the Resistance and the Allies, by receiving and transmitting radio messages from France, is relatively unknown, so the reader learns a lot about the operation and its history. The characters, Grace in 1946 and the girls and their boss, Eleanor, during the war, are vividly portrayed, memorable and distinctive. Jenoff does a good job of creating tension surrounding the war time action and of building uncertainty surrounding Grace's efforts to discover the real story. This is a good, solid read for both adolescents and adults, even including a bit of romance.