A typical war time Republic Pictures serial, G-Men vs. the Black Dragon featured the combined efforts of three allied operatives -- Rex Bennett of the USA (Rod Cameron), Vivian Marsh of the British Secret Service (Constance Worth, an Australian) and Chang Sing (Roland Got) of the Chinese counter-espionage division -- who battle the Japanese Black Dragon Society. Headed by the maniacal Oyama Harushi (Nino Pipitone, Sr.), the notorious society conducted a campaign of terror and sabotage against America until stopped by the united heroes in the 15th and final chapter, "Democracy in Action." That the Japanese master spy was played by an Italian-American was only par for the course. Much of the footage from this serial -- including a spectacular exploding submarine -- was re-used many times over, notably in the 1951 serial Flying Disc Man from Mars.
by Hans J. Wollstein synopsis