A special episode of "Sherlock" titled "The Abominable Bride" will air on Jan. 1, 2016.
According to Deadline, the special episode will air in the United States and United Kingdom on the same day.
Show runner Steven Moffat recently made this sudden announcement along with announcing that the filming of Season 4 will start April 2016 onwards, according to Comic Book. He added that currently the scripting for the fourth season is in the last stages. This implies that "Sherlock" Season 4 seems to be a far way off, so fans will need to make do with the New Year special episode for the time being.
When talking about the expectation from the upcoming season, Moffat said that the viewers can expect certain changes in the Sherlock verse. The show will also be set in a Victorian era. He further revealed that the show will not include the rude Sherlock as seen till now. He will be portrayed as a changed man altogether.
Sherlock will be more polished and will speak and behave like a Victorian gentleman. Moffat also said that Dr. Watson will become more uptight this season onwards. He also added that there will be absolutely no explanation about time travel in this season, as it may confuse the viewers a lot.
As the show's directors never bothered to explain about the settings of modern London, they are not going to explain the Victorian London setting as well.
It is rumored that a ghost is involved in this season of "Sherlock." Moffat had talked about it earlier, saying that ghosts always make for interesting plots.
The exact date of the show's release is yet to be revealed. However, the excitement and the anticipation that surround this upcoming season is at an all time high.