French Resistance networks collapsed with alarming regularity during the Second World War, and British agents parachuting into occupied France were captured almost as soon as they landed. This film investigates how deep German penetration of SOE and resistance circuits actually went, focusing on a double agent who reported to both the Nazis and the British and may have answered to a third handler besides. Historians walk through the wartime intelligence bureaucracy, contrasting SOE's sabotage-and-resistance mission with SIS's traditional espionage priorities, and asking whether rivalry and poor coordination between Britain's secret services did as much damage as any German mole. Archival documents, wartime photographs, and expert interviews build the case study around specific betrayals and captures rather than generalities, tracing how one compromised agent's contacts could unravel an entire network. The film treats the mole's true loyalties as an open question rather than a solved case, leaving the extent of the damage, and who ultimately benefited from it, unresolved by the end.