Dusko Popov ran double for British intelligence during the Second World War, feeding fabricated intelligence to his German handlers while reporting to MI5 under the codename Tricycle. This film traces his career from Belgrade playboy to double agent, using archival footage, documents, and historian interviews to lay out his two biggest claims to fame: a pre-war warning to the FBI about a Japanese interest in Pearl Harbor that went unheeded, and his role feeding the Nazis false material about the D-Day landings as part of the Fortitude deception. It also tackles the persistent rumor that Ian Fleming knew Popov and drew on his womanizing, high-stakes gambling persona when inventing James Bond. Interviews with historians weigh how much of that connection is documented fact versus legend built up after the war. The film treats Popov's private life, including his casino exploits and romantic entanglements, as part of the same story as his espionage, without losing the thread of what his intelligence actually changed on the battlefield.