The Christmas season is right around the corner, which means that the highly anticipated air date of "Sherlock" season 4's Christmas special will finally come out soon.

But less than two months prior to its still unrevealed release date, the details of the episode remain scarce except for the episode's eerie trailer that was released by BBC earlier this month.

Based on the trailer, the Christmas special will focus on a 19^th century case that Sherlock Holmes (Benedict Cumberbatch) and Dr. John Watson (Martin Freeman) will try to unlock. It involves the mystery of stolen rare jewelry believed to have been taken by a plumber known for having a felony record. But unlike the regular season of the TV series, "Sherlock" 2015 Christmas special will be set in the 19^th century Victorian era.

Series co-creator Steven Moffat told Entertainment Weekly earlier this month that the Christmas special for "Sherlock" this year will not be connected to the regular season run but has a big impact on the overall plot of the series.

"We wouldn't have done the story we're doing, and the way we're doing it, if we didn't have this special. It's not part of the run of three episodes," Moffat shared with the online publication before he joined a panel during the South by Southwest event last March. "So we had this to do it – as we could hardly conceal – it's Victorian. [Co-creator Mark Gatiss] and me, we wanted to do this, but it had to be a special, it had to be separate entity on its own. It's kind of in its own little bubble."

Meanwhile, actress Amanda Abbington told Radio Times that the upcoming Christmas special will be a great episode. The actress who portrays the role of Watson's new wife Mary Morstan said that the upcoming special is "not what you think." Though she can only share a few details regarding the episode's plot, the actress teased that the Christmas special will be "great."

"Sherlock" season 4 Christmans special is to air worldwide during Christmas day.