Sherlock Holmes (Basil Rathbone) and Dr. Watson (Nigel Bruce) are searching for a kidnapped scientist whose invention may decide the fate of World War II. Both the Allies and the Nazis are in a desperate race to possess it for their own benefit. As Holmes and Watson close in on the missing scientist, they are confronted by their diabolical nemesis, Professor Moriarty (Lionel Atwill), who has aligned himself with the Nazis.
