A new promotional photo of Benedict Cumberbatch and Martin Freeman for the Sherlock 2015 Christmas Special caused a frenzy among fans when it was released by producer Sue Vertue. The TV mastermind posted the snap on Twitter, giving viewers a first glimpse into the show's Christmas special.
The image suggests that Benedict, who plays protagonist Sherlock, and his co-star Martin, best known as sidekick Watson, will go back in time in the upcoming episode that is set to air in December 2015.
The pair are dressed in full Victorian garb, which hints that time-travelling will feature in the episode, or that the script pays tribute to the original detective series by Sir Arthur Conan Doyle.
"#221back #Sherlock #notkidding," Sue captioned the photo, making reference to Sherlock’s address of 221B Baker Street.
The BBC producer also tweeted an image of the draft script, bound and dated from 22 November, which instantly gained thousands of likes from Sherlock fans.
"This is what we've been doing today! Later on a pic of Sherlock and John as they'll appear in the Special #221back," she wrote.
Filming for series four will commence in January and appear on TV the following year in 2016, after the 2015 Christmas special.
Benedict, whose latest projects include The Imitation Game and Hamlet, has previously spoken about the "phenomenal" script for the upcoming series.
"I can't give any plot away… but their pitch for the Christmas special and the series beyond that is just phenomenal," Benedict told Empire. "We've never seen (Sherlock) being really pressed yet, so that will be interesting."
Benedict Cumberbatch and Martin Freeman on set (pictured in 2013)
"As long as the ideas are still there and the audience still wants it, and as long as Martin and I are not too infirm that we can no longer remember lines and shuffle around the set, I'd love to do it into old age, I really would," he said.
Meanwhile, Sherlock creators Mark Gatiss and Steven Moffat have already said they have "devastating" plans for the fourth series.
Speaking at the Emmys in August, the pair said, "We've practically reduced our cast to tears telling them the plan. We're probably more excited than we've ever been about Sherlock. We've got a very, very good set of ideas."