At the end of The Six Thatchers (S4 e1 of the BBC TV series, aired 1st January 2017), Mary Watson said:
Go to hell, Sherlock.
This occurs right at the very end of the episode.
Mary Watson hadn't indicated any particular animosity either during the episode or in previous episodes. In fact, she and Sherlock generally seemed to get on quite well, with her helping him out in cases, etc. It's even more confusing, given that she just gave Sherlock a (rather personal) case.
Why did she say this and what does it mean?
I thought perhaps it is simply be that she had deduced that he is the most likely cause of her death. But it still seems a bit odd and out of place.