10 Ways Sherlock Went From Great To Terrible
5. Mary Watson, International Assassin
Mary Watson is a difficult character because in the books she never leaves the house and just acts as an obstacle between Sherlock and John. Bringing to life an essential part of the Sherlock mythology but making sure to chuck out all the sexist Victorian cliches was a difficult task for the modern show and one they ultimately failed to do.
After a strong debut in The Empty Hearse by the charismatic Amanda Abbington we learn that Mary is both very funny and much smarter than John. However, the season finale reveals Mary to be an international assassin with a ludicrous backstory which truly was the moment Sherlock jumped the shark.
Moffat and Gatiss rightfully agreed to give Mary a more prominent role in the series than the books but decided the only way to make her an interesting character was to give her a preposterous occupation like 'international assassin'. Even the most loyal Sherlock fans rolled their eyes at this reveal. Even worse than this, Mary's story - from her first appearance to her death - is bundled into four episodes which gives an audience very little time to bond with her and rushed her narrative immensely.