"The Final Problem," on the other hand, is a much more intriguing answer, since it will be the third and final episode of Sherlock Season 4. Not much is known about it at this point, although Benedict Cumberbatch has shared that the end of Season 4 feels like the "end of an era" and that it will be "pretty hard to follow on immediately." That said, Sherlock has pulled off the impossible before. The Season 2 finale seemed to kill off both Sherlock and his nemesis Moriarty; Sherlock was revealed to have somehow survived by the end of the episode, and the series never really confirmed how it is that he pulled it off.