Black Dragons is a short war era thriller starring Bela Lugosi as Dr. Melcher/Monsieur Colomb. It is one of the earliest of Hollywood's responses to the bombing of Pearl Harbor and involves a group of Japanese "Black Dragons" who, through the help of the good doctor, undergo plastic surgery to look like prominent American Industrialists. Their goal, of course, is to sabotage America's war effort. However, one by one they are being "mysteriously" murdered. Wonder who? Well, there's no need to guess and no surprises in this film. The bad guys are killed and America is safe again. [Cue the waving American flag and the closing credits.]
Lugosi gives a lack luster performance here. This is probably due to his addiction to morphine as well as crippling arthritis. However, I can;t fault a guy for trying to earn a living! Even for Lugosi fans, this one can be skipped over for much finer performances from the same era such as The Return of the Vampire (1945).
For more info check out the film's entry in IMDB.