In court for murder, Professor Moriarty is released seconds before Holmes arrives, too late, with vital evidence. Free again Moriarty vows to Holmes that his next crime will be so fiendish and amazing that Holmes's reputation will be finished. Moriarty sets about a fiendish plot involving the crown jewels and a series of mysteries to distract Holmes's mind.
I enjoy most of this series as they all seem to run to the same formula. Here the plot goes back to basics and adds more of the mystery and less of the comedy. The plot is an enjoyable battle of wits between the two great minds. The downside is that the side-mystery that Moriarty sets up takes up the majority of the time and the two don't cross swords as well as they do in a gentlemanly beginning. The mystery surrounding Miss Brandon works OK but not really great as you know the whole time who is behind it and why. The jump to the crown jewels is too easily made and is a bit of a letdown.
The comedy is less evident than usual but is still there. However it is overwhelmed by the more serious side. Bruce still does well but I was glad that he stood up to Holmes more than usual – telling him off for treating him like a child and such like. Rathbone is a good Holmes but his logic was off here and I wasn't as impressed by him as I usually am. Zucco is an interesting foil, but doesn't get enough time to work here. Lupino in an early role is interesting but a little too heavy and tads to overplay her tension a bit.
Overall this is an OK addition to the series. The plot is reasonable but focuses too much on the diversion than the central characters and the reduction in comedy makes it feel a lot heavier than usual.