Well, it’s obviously a play on the title of the original Sherlock Holmes story, The Sign of Four. And this is very significant because it’s the story in which John Watson meets and falls in love with Mary Morstan, who he eventually marries.
News broke a few weeks ago that Martin Freeman’s partner Amanda Abbington would be joining the cast playing, “a role that significantly impacts upon the lives of John and Sherlock”. Speculation was already growing that Amanda would be playing Mary Morstan and today’s news compounds that theory rather nicely. Given that the second key word to describe the series was revealed to be ‘Wedding’ last year, it now seems highly likely that John will indeed meet, fall in love with and marry Mary Morstan.
But it is worth remembering that the creators of Sherlock do like to mess with our heads. Remember the very first episode and how it led us to think that Gatiss was playing Moriarty rather than Mycroft? They do love to tease us with misleading clues and of course, that cliff-hanger ending which concluded series two was the biggest tease of all.
Perhaps Amanda will be playing Harry Watson, John’s alcoholic sister? Perhaps she’ll turn up at his wedding drunk and reveal a tantalising secret which sets Sherlock and John off on a new adventure? Or perhaps she’ll be a villain, a female colonel Moran or Charlie Milverton?
I know what all the clues point to but I’m keeping an open mind just in case. And I’m off to re-read the Sign of Four . . .