Fans are already anticipating that "Sherlock" Season 4 will be as awesome as the previous one. As far the latest updates revealed, the production has already begun and expected to air in televisions next year. Here's what viewers should know:

The show's co-creator Mark Gatiss shared a sneak peek of Benedict Cumberbatch and Martin Freeman's comeback on the show's set on Twitter. The photo depicts a camera shot of the lead actor.

While the snapshot did not reveal more hints, Carter Matt believes that the production team would want to keep the filming as mysterious as it can be to add more excitement to the fans. But that did not stop the speculations to be arising on the Internet.

Parent Herald notes that fans are already guessing that Mary Watson will die from childbirth on the first episode. As per Den of Geek report, Gatiss revealed in one of his earlier interviews that Sherlock, John, and Mary will be facing a difficult situation.

"Even though Mary is very proactive and a huge part, it's a sort of breathing space between 'Vow' and the next one," he said. Although Parent Herald has the official synopsis, it does not contain what will happen to Mary but their preparation for parenthood was revealed instead.

"[Season 4] begins with the nation's favorite detective, the mercurial Sherlock Holmes, back once more on British soil, as Doctor Watson and his wife Mary prepare for their biggest ever challenge - becoming parents for the first time," as the official synopsis stated. 

"Sherlock" is expected to air on tv screens in January 2017.