In 1943, Edda Mussolini, daughter of the fascist dictator Benito Mussolini, 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 diaries to the press.

Knowing the diaries would expose Nazi lies and create a foundation for war crimes prosecutions, Hitler and Mussolini vowed to do everything in their power to see the diaries destroyed - even if it meant killing Mussolini’s daughter. To do this, they ordered Hilde Beetz, a German spy, to seduce Ciano in prison in order to learn the diaries’ location. However, the seducer became the seduced, joining forces with Edda to try to save Ciano from execution. When this failed, Edda fled, with Hilde’s daring assistance, to keep Ciano’s final wish: to see the diaries published for use by the Allies.

Upon learning of Edda’s escape, the head of United States intelligence, Alan Dulles, sent in socialite Frances de Chollet, assigned by chance to a mission that would change her life. Her task was to find Edda, gain her trust, and, crucially, hand the diaries over to the Americans. Against all expectations, what developed was a rich and humanising friendship between the two women. Staying one step ahead of the Gestapo agents who were hunting Edda, together they succeeded in preserving one of the most important historic documents of World War II.

Containing all the detailed twists and turns of a spy thriller, this is the story of three women, each faced with unbearable pressures and weighty moral questions, whose lives were drawn together in one of the most unlikely rescues of World War II.