PBS (via TVLine) has released the first official image for "Sherlock" season 4, focusing on the main stars Benedict Cumberbatch and Martin Freeman as Sherlock Holmes and Dr. John Watson respectively. As reported by Screen Rant, Watson is notably sporting a new hairstyle and has gotten rid of the moustache he wore in season 3.

The report further points out that the image continues to depict a somber, darker tone and this would further imply that season 4 is going to be darker than previous seasons, even darker than the already violent season 3. The report points out that the teaser trailer shown at Comic-Con also had a dark, brooding and foreboding tone, further hinting that season 4 will push the series over the edge.

According to the report, Sherlock will have to face his demons as he also fights to stop the season's main villain, Culverton Smith (Toby Jones). There is also the issue of Moriarty (Andrew Scott) causing trouble for the heroes despite him already being dead. Fans speculate Moriarty had planned things ahead just in case he'd die and Sherlock survived.

TVLine also reveals that while Sherlock is busy solving cases regarding Moriarty and Culverton, Watson and his wife Mary (Amanda Abbington) will be facing another problem: pregnancy. Mary has been confirmed pregnant although it is unconfirmed where this story arc may lead given that in the original short stories and novels Mary died and never had a child with Watson.

"Sherlock" season 4 is touted to be the beginning of the end as it might be the very last season for the series. Both Cumberbatch and Watson are contracted for multiple roles in the Marvel Cinematic Universe, particularly Cumberbatch as he plays Doctor Strange. This busy schedule may prevent further seasons of "Sherlock" being produced.

No official release has yet been but it is launching sometime in January 2017.