17 Things You (Probably) Didn’t Know About Sherlock

Amanda Abbington Didn’t Know Mary’s Backstory for Most of Season 3

Actress Amanda Abbington joined the cast of Sherlock in Season 3, playing the role of Mary Morstan. In the Sir Arthur Conan Doyle canon, Mary is John Watson’s wife, who appears briefly in a handful of his tales and then dies between stories of mysterious circumstances. Her character has a considerably larger role in this television version. John meets her during the period when he thinks that Sherlock is dead, and the two marry in the episode after the detective’s return.  But Mary harbors a fairly significant secret – and a dark past. As it turns out, she’s a former assassin who changed her name to hide from her past and has lied to John about virtually every aspect of herself. (Mary Morstan isn’t even her real name.)

This twist is not only a fairly major divergence from established Holmes canon, it’s also a massive shock within the world of the show itself.  And the news of Mary’s secret identity wasn’t just a surprise to viewers – it was a shock to the actress who played her as well. Abbington was unaware of Mary’s backstory while filming Season 3’s first two episodes. She only learned of the season’s big twist once she got the script for the finale “His Last Vow”. (Apparently Steven Moffat and Mark Gatiss just told her Mary “had a secret”.) This impacted the way the actress chose to portray the character of the course of the season, for good or ill.

“I’m playing it all very innocently. I would have played her differently, had I known her backstory”, Abbington said during the episode commentary.