Fans of "Sherlock" have been waiting for more episodes to air since the show's season 3 finale. While the show has gained positive reviews and stellar ratings, it also has the least number of episodes as "Sherlock" has only aired nine episodes since its premiere in 2010 up to the season 3 finale last year.

But prior to the season 4 premiere, which is expected to air sometime next year, the series' fans in the UK will be treated to a special episode, which is expected to air on Christmas Day.

In the first look trailer for the "Sherlock" Christmas special, Holmes (Benedict Cumberbatch) and Watson (Martin Freeman) have just arrived on Baker Street, and the two are about to make their way to Holmes' apartment at 221B. The two are greeted by Mrs. Hudson (Una Stubbs), who tells the detective that she wishes that he would tell her that he was planning to come home.

"I hardly knew myself Mrs. Hudson, that's the trouble with dismembered country squires, they're notoriously difficult to schedule," Holmes quips, before sticking his pipe in his mouth.

Mrs. Hudson tells Watson that he has published another one of his stories, and when asked if she enjoyed reading it, she replied, "No."

"I never enjoy them… I never say anything in them, do I?" said the landlady about the story. "According to you, I just shove people up the stairs and serve you breakfast."

"Don't feel singled out, Mrs. Hudson. I'm hardly in 'the dog one,'" said Holmes.

"The dog one? You mean 'Hound of the Baskervilles?'" asked Watson.

The special is based on Conan Doyle's short story, "The Adventure of the Blue Carbuncle," which tells the theft of a priceless jewel from the hotel suite of the Countess of Morcar. Showrunner Stephen Moffat told Collider that the special—a Victorian version—will not be a part of the series but is an "extra," adding that they wanted to make it as close as possible to Doyle's story.

As for season 4, Moffatt said that writer Mark Gatiss will be writing the episodes soon and that shooting will start "next year, April-ish."