Following a brief glimpse of footage in a new BBC promo that debuted last month,Masterpiece PBShas unveiled a full trailer for the highly-anticipatedSherlockspecial, which still doesn’t have a premiere date in place at this time. Unlike the regular series which is set in present day, thisChristmas specialtransports both Sherlock Holmes (Benedict Cumberbatch) and John Watson (Martin Freeman) all the way back to the 19th Century, where Sir Arthur Conan Doyle’s original Sherlock Holmes stories took place. While it isn’t known why this crime-fighting duo have been transported to the Victorian Era, we do get to seeSherlockput on a very special hat.

It was revealed atComic-Conthis summer that theChristmas Specialwill arrive sometime in December, and fans will also get the chance to watch the special in selectmovie theatersin the U.S. Executive producerSteven Moffattold the SDCC crowd that this is one of the finest episodes they have ever produced, and he even considered shifting the series to this time period, permanently. The first trailer offered a reference to the show’s long absence, which hasn’t aired a new episode since early 2014, withBenedict Cumberbatch’s Sherlock Holmes telling his landlady Mrs. Hudson (Una Stubbs) that “dismembered country squires” are “notoriously difficult to schedule,” referencing the actor’s own increasingly busy slate of productions.

This special will be followed by the long-awaitedSeason 4ofSherlock, which will be comprised of three 90-minute episodes, airing sometime in 2016. It isn’t known when production will begin on the new season, butSteven Moffatsaid in March that the new episodes will be “bloody frightening” and much darker than the first three seasons. No new characters have been confirmed forSeason 4yet, but we could see the return of another familiar face.

Sherlock Season 3featured Holmes returning from the dead to watch his best friend John Watson marry Mary Morstan and square off with his ultimate nemesis 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? It still hasn’t been confirmed yet if Andrew Scott will return as Moriarty, who was killed off at the end ofSeason 2, but the actor did make a surprise appearance in a video shown to fans at SDCC.

Sherlockis written and created bySteven Moffatand Mark Gatiss, and inspired by the works of Sir Arthur Conan Doyle.Sherlockis produced by Sue Vertue and the executive producers are Beryl Vertue, Mark Gatiss andSteven Moffatfor Hartswood Films, Bethan Jones for BBC Cymru Wales andRebecca Eatonfor Masterpiece. While we wait for more details on this highly-anticipatedSherlock special, check out the new trailer.