Juan Pujol García, a Spanish civilian with no loyalty to either side, talked his way into German intelligence and became one of the most consequential double agents of the Second World War. Working for British intelligence under the codename Garbo, he invented an entire network of fictional sub-agents, complete with fabricated reports and expense claims, feeding the Abwehr a stream of intelligence designed to look real while steering it toward Allied advantage. The film traces how his fabricated network convinced German high command that the D-Day landings would fall at Calais rather than Normandy, a deception that helped keep German reserves pinned down for weeks after the actual invasion. Historians and archival documents lay out how Pujol built and sustained the ruse without formal training, and how both Britain and Germany ended up decorating him for his service, each unaware of the other's judgment. Interviews and period material reconstruct a story of a man who fought fascism not with weapons but with paperwork and invention.