My personal favourite of these Rathbone/Bruce combinations. This time, the fiendishly clever Professor Moriarty (George Zucco) intends the crime of the century and so has Holmes and Watson distracted by an ominous series of murders whilst he sets about perpetrating his true desire. Henry Stephenson also chips into this accomplished murder-mystery that keeps you guessing for quite a while. The atmosphere of a foggy London all adds to the dramatic effect of this film and Rathbone and Bruce are clearly now on their way to establishing their own, definitive, characterisations of their fictional alter-egos.