During Sherlock's Comic-Con panel, the series debuted the first trailer for their highly-anticipated Christmas Special, which doesn't have a specific air date quite yet. Earlier today, BBC released a special trailer highlighting their fall/winter lineup, which includes brief snippets of new footage from Sherlock's Christmas Special. The Sherlock scene shows Benedict Cumberbatch's title character smoking a pipe, stating "From the beginning, then."

The last season saw Sherlock's life change a lot - he returned from the dead, his best friend John Watson married Mary Morstan and he met his match in Charles Augustus Magnussen. After the briefest of exiles, Sherlock came back only to face one of his biggest mysteries yet. Why is Moriarty's face being broadcast on every television in the land? The Christmas special will be followed in 2016 with Season 4, which, like previous seasons, will be comprised of three 90-minute episodes.

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The Christmas Special is set in Victorian Era London, the same era when Arthur Conan Doyle's original stories take place. Steven Moffat revealed at Comic-Con that he hasn't started writing Sherlock Season 4 quite yet. But he did say back in March that this season will be much darker than the first three, describing certain aspects as "bloody frightening." The Comic-Con trailer showcased a Victorian Era setting, and offers a wink to the audience regarding the show's long absence, since a new episode hasn't aired since early 2014. When Holmes tells Mrs. Hudson that he didn't know when he was coming home, since "dismembered country squires" are "notoriously difficult to schedule," it is a nod to the stars' own increasingly busy schedules which have kept them away from the show.

The Season 3 finale, "His Last Vow", ended with a cliffhanger that teased the return of Jim Moriarty, played by Andrew Scott. Star Martin Freeman revealed last year, before the Season 4 renewal was announced, that a one-off special is coming. However, we still don't have any plot details for the Christmas special or the new season thus far.

Sherlock is written and created by Steven Moffat and Mark Gatiss, and inspired by the works of Sir Arthur Conan Doyle. Sherlock is produced by Sue Vertue and the executive producers are Beryl Vertue, Mark Gatiss and Steven Moffat for Hartswood Films, Bethan Jones for BBC Cymru Wales and Rebecca Eaton for Masterpiece. It isn't known when BBC plans on releasing a full trailer for this Christmas Special, but we'll keep you posted as soon as more details come in. In the meantime, check out this new trailer.