British actor Benedict Cumberbatch (R) and his fiancee Sophie Hunter attend the Evening Standard Theatre awards in London November 30, 2014.
British actor Benedict Cumberbatch (R) and his fiancee Sophie Hunter attend the Evening Standard Theatre awards in London November 30, 2014. REUTERS/Neil Hall

"Sherlock" team will soon begin filming the one-off special episode, which is expected to air on Christmas 2015. Sue Vertue, executive producer of "Sherlock," posted the draft script of the special episode, written by Mark Gatiss and Steven Moffat, on Twitter, earlier in November. Later, she posted the first look of Sherlock and Dr Watson, who is sporting a moustache again, as they will appear in the special episode. The special episode is set to solve Moriarty's reappearance mystery.

As previously reported, the shooting of one-off episode of "Sherlock" will begin in January. It is currently in pre-production stage. Sherlock will be returning to face one of the "biggest mysteries," which is the appearance of dead Moriarty on TV screens across UK, saying, "Did you miss me?"

According to Radio Times, Gatiss has said that Moriarty's appearance mystery will be "completely" solved in the special episode. However, he refused to confirm whether it will be Andrew Scott's, who plays Moriarty, final appearance in "Sherlock." Gatiss said, "Well, it's very hard to put a lid on Andrew Scott..."

Benedict Cumberbatch, who plays Sherlock, told Empire that the writers' pitch for "special episode and the series beyond that is just phenomenal. We've never seen [Sherlock] being really pressed yet, so that will be interesting."

The reappearance of Moriarty stopped Sherlock from going on a suicide mission to Eastern Europe, after he shot Charles Augustus Magnussen, the "Napoleon of blackmail." It is expected that the solution of Moriarty's mystery will pave the way for the introduction of a new antagonist in Season 4 of "Sherlock."

It has not yet been announced when the production on the three episodes of "Sherlock" Season 4 will begin. It is expected to take place in the second half of 2015. However, the busy acting schedules of Cumberbatch and Martin Freeman, who plays Dr Watson, may push ahead the production date once again.

Cumberbatch has signed on to star in "Doctor Strange." He is playing the titular role. The movie is scheduled to hit the movie theatres on Nov. 04, 2016. The production is expected to begin in spring next year.

Contact the Writer at a.shrivastava@ibtimes.com.au.