Sherlock Holmes protects a scientist who is persecuted by the Nazis and who has developed a new bombsight, which he plans to give to the british army. To be sure, he dissasembles his invention and sends it to four other scientists, whose names he encodes and notes down. Prof. Moriarty, Holmes' nemesis, tracks three of the four scientists down and kills them for the machine's parts. Yet, the fourth name is severely encoded and Holmes as well as Moriarty have problems finding said scientist. They race each other for the name and Holmes is being captured by Moriarty.