Sherlock Season 4 will begin filming for new episodes early next year as Benedict Cumberbatch returns to his investigation with a winter premiere. Fans will also be treated to a one-episode special this Christmas holiday season in a Victorian era which is a standalone story not connected to the upcoming season.

An IDigital Times report has pegged the new season premiere during winter 2016. However, this remains unconfirmed by Sherlock showrunners.

Promotions for the one episode special indicate that the holiday treat for fans will have Sherlock Holmes, played by lead star Benedict Cumberbatch, back in the Victorian era in the 1890s. The stand-alone special will come out in select theatres and on television.

Showrunner Steven Moffat was earlier quoted in reports explaining the inspiration for the setting to go back to the time in which writer Sir Arthur Conan Doyle wrote the stories about Sherlock Holmes.

Moffat revealed at the BAFTA TV Awards, "We've got, I think you can safely say, the Sherlock Holmes and Dr. Watson of a generation - we want to see them do it in the proper outfits, just once."

The alternate setting will also highlight the series' deviation from the original stories, particularly in providing more speaking lines to the female characters, according to Entertainment Weekly.

Moffat reveals, "In the original stories, none of the women really speak. They just don't talk unless it's specifically germane to the plot. So it was a challenge for us in terms of what we're going to do with our female characters now that we're back in Victorian times ... which sort of became quite central to how we handled it."

Co-creator Mark Gatiss has hinted on Twitter the special episode could be based on Doyle's 1892 story on The Adventure of the Blue Carbuncle involving the theft of a jewel and plumber with a felony record being arrested for the crime. Gatiss tweeted a quote from the story, "...it was a bitter night so we drew on our ulsters and wrapped cravats around our throats." 

The reference to the specific Doyle writing has been bolstered by director Douglas Mackinnon's post also on Twitter and also from the same 56^th short story about Sherlock, "The stars were shining coldly in a cloudless sky."

In the meantime, the Sherlock Season 4 series story plot is yet to be teased although Moffat is reported by Youth Health to have revealed the series would be about "consequences, coming back to bite you."

What is definite though is the return of Cumberbatch as Sherlock Holmes, and Martin Freeman as his best pal Dr. John Watson. The two have increasing commitments to various films but have committed to returning to the series.

Sherlock is presented by the British Broadcasting Corporation as a reimagining of the duo's adventures in 21^st century London.