IF they are taking anything from the Noble Bachelor - the story goes that it's on her wedding day that her husband, whom she previously thought dead, turns up at the wedding and so she goes missing during the Reception.
It would be too delicious a storyline for Gatiss to miss. It's the only story in the Canon which features a wedding. Someone from the past haunting the bride......
Oh and you know when Watson was kidnapped and put in the bonfire? They never got to the bottom of that did they? But that was the point which drew Watson and Sherlock back together. Mary was really gunning for Watson to meet Sherlock again but he refused, then he was kidnapped and Sherlock saved him. What was the motive?
Who did Mary go running to when Watson went missing? How did she know the text was a code?
Sorry to say that I think they do make Mary a bit of a bad 'un, after all they've taken liberty with other characters and Mary was hardly a major player in the books.