Another Holmes WW2 propaganda crime story that has dated a lot. An important clue regard a "Dancing Men" code that is way too short for the long sentences Holmes manage to translate out of it. Luckily the film also has an appearance by Holmes' arch-enemy Moriarty who is always a fun villain to put up against Holmes and there is a fun scene where Holmes gives the villain the best idea to kill him.
Oh look at that, Moriarty's back. A serviceable propaganda entertainment, but often preposterous (which Holmes, really, should never be regardless of time period). Is it smart that Holmes gives Moriarty the idea for his excruciating and unbelievable torture? Or ridiculously stupid? We'll never know.