In a new trailer for the here-to-for unnamed Sherlock special that takes them back into the 19th Century, the title and airdate for the special were finally revealed. The episode is called "Sherlock: The Abominable Bride" and will air on January 1, 2016.
The special stars regular series stars Benedict Cumberbatch and Martin Freeman as Sherlock Holmes and Doctor Watson, respectively, but unlike the other episodes of the show that take place in the modern day, this one goes back to the characters' roots.
That means a bushy mustache on Watson, and the classic pipe for Sherlock. Oh, and as Freeman says in such a gloriously meta moment in this trailer and the last, "You're Sherlock Holmes. Wear the damn hat."
Sherlock from Steven Moffat will then return to filming in 2016 for a full fourth series, jumping back to the present day and continuing the story of the three episode, 90-minute prior three series.