Back in the 2016 San Diego Comic Con, Mark Gatiss, who plays the role of Mycroft Holmes, and who is also the co-creator and writer of Sherlock, confirmed that they are two week from finishing Season 4 at that time, and all is going very well. Fans been treated to a teaser trailer for Sherlock Season 4 at SDCC, which gave very little of the coming plot away, other than the fact that Sherlock is alive, and will probably face a new adversary.

According to Parent Herald, co-writer Gatiss and Steven Moffat promised fans that the season 4 of Sherlock will have shocking reveals and castings. Their word may hold true when a fake trailer for Sherlock season 4 caught the attention of fans. The trailer teased of actor Tom Hiddleston, who is best known for playing the role of the villain "Loki" in the Marvel movies, wass shown playing the role the third Holmes brother, Sherrinford. The trailer was riddled with cleverly placed scenes from Sherlock and Hiddleston's "The Night Manager."

Fans have been excited with the premise of the trailer, and rumors keep popping-up about getting Hiddleston to join Sherlock in season 4. But sadly, there is still no confirmation if Hiddleston will be joining Sherlock on his adventures. Tom posed for a photo with Mark Gatiss and Amanda Abbington, who plays Mary Watson in the series. Gatiss further fanned the flames for the rumors of Hiddleston's involvement with Sherlock, and tweeted out the said photo with a a caption, "Blud" which is a term that means a brother that is not related by blood. Could this be a sign that talks are in progress to making this fantasy casting into a reality?

Digital Spy reports that joining the cast will be veteran actor Toby Jones, who most will recall was in various Marvel movies protraying the character of Arnim Zola, a villain who was first introduced, in "Captain America: The First Avenger." He is said to play the role of season four's big baddie. From glimpse of Jones' scenes in the trailer, there seems to be a insanity and deviousness to his character - someone that may prove to be a worthy rival for Holmes.

Season 4 of Sherlock is expected to air on The BBC in January 2017.