"Sherlock" season 4 is still far off, with 2016 still an unlikely release date for the much-awaited new run of the BBC hit. Thankfully, a Christmas special is on the horizon, complete with a trailer for fans to get a glimpse of the new adventure the greatest detective of all time is in.

According to iDigital Times, the one-time special could be based on a short story written by Sherlock Holmes creator Sir Arthur Conan Doyle back in1892. It is called "The Adventure of the Blue Carbuncle," which pits Sherlock against a plumber who is accused of stealing a jewel.

In the trailer, Sherlock and Watson are in the Victorian era. The trailer is intense and a lot of action is happening. There's a scene where Sherlock is questioned for his apparent inability to keep a certain someone safe. There's also one where the sleuth realizes that what they are in is war.

Certain scenes in this pre-"Sherlock" season 4 special are of Watson, who questions why and how the detective changed.

Asked by his right hand man, "What made you like this?" Sherlock responded "Oh Watson, nothing made me. I made me." A scene of Sherlock drawing out a gun and pointing it at someone is then shown.

The full-length trailer for the episode does not reveal when the Christmas special will air. What's sure is that it's in the offing, although fans remain clueless of how long they actually have to wait to see Benedict Cumberbatch and Martin Freeman doing detective work on the small screen again.

Showrunner Steven Moffat has always been tight-fisted as far as spoilers go. The last time he talked about the special episode was back in July with BBC News. There, he quipped "It's like we checked the books and discovered we'd set it in the wrong time period by mistake and it's like we're correcting it for 90 minutes." He added, "We're really proud of it, we think it's a real cracker. But that'll be it until series four."