In 1943, Edda Mussolini, daughter of the fascist dictator, gave her father and Hitler an extraordinary ultimatum - release her husband, Italy's former foreign minister, Galeazzo Ciano, from prison, or risk her leaking her husband's incendiary diaries to the press.

Instead, Hitler and Mussolini vowed to do everything in their power to destroy the diaries - even if it meant killing Edda. They ordered Hilde Beetz, a German spy, to seduce Ciano in prison in order to learn the diaries' location. But Hilde fell in love with Ciano, and joined forces with Edda to try to save him from execution. When this failed, Edda fled with Hilde's assistance.

Upon learning of Edda's escape, US intelligence sent in socialite Frances de Chollet to find Edda and get her to hand over the diaries to the Americans. Against all expectations, what developed was a rich and humanising friendship.

With all the twists and turns of a spy thriller, this is the story of three women whose lives were drawn together in one of the most unlikely rescues of the Second World War.