Very Special Agent Fifi was described as ‘one of the most expert liars in the world’. Employed by the Special Operations Executive (SOE), Churchill’s wartime spook organisation, her job was to entrap trainee agents and test their mettle in the field. Kept secret for seventy-five years, her existence long treated as a myth, Fifi’s files were declassified in 2014 and her identity revealed. She was Marie Chilver, a half-Latvian, half-British escapee from occupied Europe. Marie’s extraordinary story reveals the inner workings of Britain’s secret services and the lengths the SOE would go to in equipping their agents for their highly dangerous espionage work in Nazi-dominated Europe.