So, series two is starting to take form, with the second episode just as good as the first. I needn't bore you with the trivial talk of how much the series has improved, or how much was riding on this episode being as good as the last, because you all know that as well. Needless to say, you can all take comfort in the fact that you won't be disappointed with this episode.
I remember sitting in maths lessons and thinking that Pythagoras was the trickiest equation I would ever have to see, until I saw this episode, where the problem is whole lot deadlier. Sherlock and Watson are on the case to solve the mystery of two dead mathematicians on the brink of solving one of the greatest math's problems: P vs. NP. Sounds very straightforward, but this episode is far from straightforward.
Watson also has a bigger role this week, when she bumps into the son of a man who cost her career as a surgeon. She has to make the tough emotional decision when he asks her for a large amount of money. This seemed like a good side element for this episode, because it gives you the chance to learn more about Joan's back story, and what led to her decision to become a sober companion.
Another striking element to me was Sherlock becoming a worried friend to Joan. Yes you saw that right! When Joan turns to Sherlock to forward some of her pay to give to the young man who is the son of the man who cost Joan her career...and breathe...he offers her advice so that she doesn't make the wrong decision. He shows concern for Watson, which is when the fandom will undoubtedly kick off with a "will they/won't they" scenarios. Watch out fan-fiction...
Overall, another good episode, if not a tad predictable as we neared to the end, but enjoyable anyway. It was really good to see the writers come up with a plotline and a premise that is totally believable, yet seems so far away that it seems impossible...well played Sherlock, well played...