It was reported that "Sherlock" will begin production for its fourth season this 2016.
Executive producer Steven Moffat recently shared that the season will surprise fans. He said that the events to come will be the last thing people will expect. He also added that it will be better than season 3, even receiving a tearful response from the cast after hearing the plans, according to Entertainment Weekly.
The upcoming season is expected to explore darker themes, compared to the past seasons. It was speculated that Mary will eventually die in the series, as it was her fate in the short stories.
Moffat said, "We're going to try to take it somewhere we've never been before — and I don't mean outer space. It will be a challenging place to go. We always start with a re-introduction that builds toward a darker climax — we might just be going darker [from the outset]. We got a very, very good set of ideas."
But before the premiere of the fourth season, the series will release a special that is set in the Victorian Era. Going back to the origins of the short stories, the special is expected to be a stand-alone narrative and not at all connected with the season to come.
As for the special, Moffat stated, "The special is its own thing. We wouldn't have done the story we're doing, and the way we're doing it, if we didn't have this special. It's not part of the run of three episodes. So we had this to do it — as we could hardly conceal — it's Victorian. [Co-creator Mark Gatiss] and me, we wanted to do this, but it had to be a special, it had to be separate entity on its own. It's kind of in its own little bubble."
Sherlock season 4 is expected to premiere on 2017.