Purnell gained a wide following with her acclaimed biography of Clementine Churchill. Her new book tells the previously untold story of Virginia Hall, an American who, after being rejected from the Foreign Service, went to England and became one of the greatest spies in history. The first woman to be deployed to occupied France, Hall soon became known as the “Madonna of the Resistance” for her skillful coordination of a network of spies. To the Nazis she was “the most dangerous of all Allied spies” and they were determined to be rid of her. Hall ignored orders to evacuate and when her cover was blown, she made a harrowing escape over the Pyrenees—then returned to organize sabotage against enemy lines and prepare for the Normandy landing.