As often is the case with special episodes, it doesn’t advance the plot a whole lot. We see Sherlock and John in Victorian times, like the original Sherlock Holmes. That’s why this episode cleverly incorporates many features of the original Sherlock Holmes more explicitly than the series usually does: His drug addiction is even more serious (we learn his mind palace technique is fueled by drugs), the Victorian setting itself is fun to watch, Watson is even more of a narrator, which is openly acknowledged and we have the actual Reichenbach Fall. There are also many of the usual jokes but they still work.
Unfortunately, the case in the past is pretty boring and not very intriguing. Sherlock and John are to investigate the appearance (or rather apparition?) of a dead woman.
As soon as it’s revealed that this whole sequence takes place in Sherlock’s mind palace, there is a narrative frame that makes this whole thing more interesting. The case nicely mirrors Moriarty somehow being alive after being considered dead. It is nicely shown that Moriarty is his biggest weakness and that Sherlock has a true admiration for Watson. Sherlock overcoming Moriarty in his inner fight is the most interesting aspect of this episode.
The scene with insanely fat Mycroft was something I didn’t need and it served no real purpose.
The episode end is a nice bridge to season 4 as Sherlock returns and has come to the conclusion that Moriarty can’t be alive and that his allies sent out this message. The very end joke is pretty meta and funny.
All things considered a nice experiment where the writers could play out their ideas and references. It’s okay to watch without being super entertaining or insightful. The episode certainly becomes more interesting in the second half.
© by BBC, image taken from their website