‘Sherlock’ Spoiler Update: Revelations Of One-Off Special Episode, To Be Aired Before Season 4 Premiere Date

Mark Gatiss, co-creator of "Sherlock" and who plays Sherlock's brother Mycroft in the show, has confirmed that the production on the one-off episode of "Sherlock" is scheduled to begin in Jan. 2015 and the filming is likely to wrap up by spring 2015. The pre-production on this episode is said to be already underway. Gatiss, however, is not sure when this special episode is going to air.

Radio Times has quoted Gatiss as saying to its deputy editor, Paul Jones, "... when they show it ["Sherlock" special episode] it's entirely down to the schedulers." He said that the special one-off episode would be an ideal Christmas special episode but added that there is no guarantee to that. Gatiss said, "they used to show the Mike Yarwood [Christmas] Show in the summertime."

He revealed they are "tremendously" excited about the special episode and called it "very, very special." Also, he said that they are close to filming this episode and more details about the episode may get spilled soon, as the fans of this hugely popular BBC series start gathering around the "Sherlock" filming location once the production begins. "It won't be long before people see enough to get their teeth into...," Gatiss said to Jones.

Radio Times has said that the special episode is likely to address the question whether Moriarty is alive or dead. The last Christmas special episode, which aired on Dec. 25, 2015, was 7-minute long. It featured Anderson telling his theories to back up his claim that Sherlock is not dead. Also in the episode, Dr. Watson received a video message from Sherlock on his birthday. In the message, Sherlock said to his friend that he will be back soon. It is likely that the new special episode may provide clues about Moriarty's existence or reveal the existence of Moriarty's twin brother. The Season 3 of "Sherlock" wrapped up with gif of Moriarty appearing on TV screen across the country, asking did they miss him.

As previously reported, there are speculations that the filming of the three episodes of "Sherlock" Season 4 may get delayed because of Benedict Cumberbatch's titular role in the "Doctor Strange" film. The actor will begin shooting the movie next year. If the production date is pushed ahead once again, it is likely that "Sherlock" Season 4 may premiere in 2017.