BBC 'Sherlock' Season 4 and Special Episode: New Trailer Released [Watch]

Enthusiasts who relish the BBC series "Sherlock" will be delighted to view the newly released trailer, which hints at events to take place during the forthcoming Victorian special.

Sherlock Holmes, John Watson and the rest of the team will be placed squarely in 19th century England. The stray, standalone episode will show Sherlock as a mild-tempered and put-together lad, differing very much from the modern version of the iconic sleuth. However, Watson will be nearly the same, although he will have a bushy mustache.

The short trailer also shows D.I. Greg Lestrade (Rupert Graves) and hint at gothic horror. The teaser also shows that the Sir Arthur Conan Doyle characters maintain their compatibility and flair, even after departing from modernity.

While at the San Diego Comic-Con 2015, executive producer Steven Moffat said, "When we first did ''Sherlock, press asked, 'How can Sherlock possibly survive in world with an iPhone?' and when doing the Victorian, the press came in and said, 'How can he do this without his iPhone?' It's very much the show you know. It's the Sherlock as you know it, but in the correct era. It's one of the best ones we've made. I think it's really terrific."

There won't be an exploration for the shift through time, although series' creators considered a dream sequence or Victorian-themed house party as an explanation for the time transport. However, Moffat told EW, "We never bother to explain why Sherlock Holmes and Dr. Watson are in the modern world in the normal series; why should we bother explaining now that we're back in Victorian times?"

In regards to the upcoming fourth season, Moffatt told Express they have a clear idea of what they're going to do, and there will be a clear shift in tone. Also, there will be dark stuff, but there will be fun and jokes and detection. It'll be dark in some ways, but "Sherlock" will always maintain a bit of humor, even when there's a sense of things coming back to bite the characters.

The upcoming special will air later this year on PBS. Also, Season 4 is expected to begin filming in 2016.