Once considered by the Gestapo to be “the most dangerous of all Allied spies”, Hall was the first female operative of Britain’s Special Operations Executive to be sent into France. She worked in three years in France as an Allied Spy. Her cover was later blown and she escaped by hiking through the Pyrenees Mountains. She later returned to France to report on the movement of German troops as a wireless radio operator. After her service in WW2, she joined the CIA in 1951.