Sherlock' Season 4 Premiere and News: Is There a Third Holmes Brother? Will Mary Watson Die? Fan Theories Emerge as the Show Release Date Still a Mystery

"Sherlock" Season 4 filming has begun and the fans around the world cannot contain their excitement for the upcoming season. However, much to the dismay of eager fans, the release data has not been confirmed yet. This season is presumably the last season of the show and will be aired sometime early or mid 2017.

Benedict Cumberbatch playing the lead, Sherlock, has also said that wait will not be that long this time. He also added, "genuinely thrilled to be back filming 'Sherlock' with all the cast and crew. I can't wait for everyone to see season four. But you will have to wait... though not for long... And it will be worth it."

However, this interminable wait has given rise to certain fan theories with regards to the upcoming season. One of the most anticipated theories is that perhaps Sherlock and Molly will get romantically involved. Even if they do get a romantic angle, Sherlock's imminent death in the next season will abruptly end their dreamy future.

Another theory, that seems more realistic and plausible, is death of Mary Watson, John Watson's wife, during childbirth. The last season has been pegged to be a dark one.

There is also another exciting rumor that Tom Hiddleston might join the show as third Holmes brother. The rumor stems from Mycroft's (Mark Gatiss) remark in show's season 3, "I'm not given to outbursts of brotherly compassion. You know what happened to the other one," suggesting that Hiddleston may be the third brother to the Holmes clan.

It has been confirmed that Daniel Hoffman-Gill will appear in the show as Gold Teeth, though his intent or fidelity is not known yet.