Even before the news that "Sherlock" was renewed for another season, BBC One already hinted the upcoming fourth season of the hit TV series and teased that the new season will be the most shocking of all. BBC One also cautioned the viewers to expect surprises and new discoveries about the characters.

Yahoo first reported that "Sherlock" will be back for a new season, but it will not be big. The report said that season 4 will only be composed of three episodes. The report added that the series will not comeback until December 2015, when the series will show a Christmas special before the fourth season officially starts. "Sherlock" season 4 is set to air in early 2016. However, there is no exact date yet as to when the series will premiere.

The Christmas special of "Sherlock" next year will reportedly be based on the story of "The Adventure of the Blue Carbuncle." However, this also has not yet been confirmed by BBC.

The filming of the "Sherlock" season 4 will start in January 2015. But the creators behind the series have already begun concocting ideas for the next season. The delay in filming is due to the conflicting schedules of the prime characters as the production team has to arrange schedules that are amenable to both characters.

Meanwhile, latest spoilers teased that Moriarty will be back next season. In an interview with MTV, Benedict Cumberbatch revealed that Moriarty is set to return in the new season. The actor also added that he was very excited to resume filming for the modern day version of the popular Sherlock Holmes mysteries.

When asked whether Moriarty (Andrew Scott) will appear again next season, the actor answered, "Yeah, I think so. I casually choose to forget in order to rediscover it again a little bit."

Other spoilers also claimed that Mary (Amanda Abbington) will return in season 4 contrary to the reports that her character will be killed off. Show creator Steve Moffat also revealed that the 221B Baker Street location will be used again.