'Sherlock' season 4 trailer revealed at Comic-Con 2016

Big reveals just kept on coming from the recent San Diego Comic-Con as the trailer for the fourth season of BBC's "Sherlock" was finally released.

The trailer teases the possible return of Andrew Scott's Moriarty. Last season, Sherlock (Benedict Cumberbatch) made sure if Moriarty really did die on that roof, but that doesn't really mean that Moriarty hasn't left something behind to mess with Sherlock and the gang. The "Saw" franchise kept on going after the death of the main villain, so how could Moriarty just let his death be the end of his torment to Sherlock?

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The trailer also shows Toby Jones joining the cast as the new villain for "Sherlock" season 4. Variety reports that Jones will be playing another one of Sir Arthur Conan Doyle's villains, Culverton Smith, who was most prominent in the story "The Adventure of the Dying Detective" — or simply just, "The Dying Detective."

But could Jones be playing more than Mr. Smith? In the classic "Sherlock Holmes," Moriarty was actually much older than Sherlock, which is a contrast to Scott's Moriarty who may even be younger than Cumberbatch. Maybe the true mastermind behind it all is Jones' Moriarty, but then again, this is all just speculation.

Fans also get a glimpse of Sherlock sporting a goatee. Cumberbatch is starring in Marvel Studios' "Doctor Strange" coming out this November, and his character has a goatee as well. Perhaps it's a subtle reference to his role as the Sorcerer Supreme, or maybe the production just wanted to save on make-up and had Cumberbatch shooting between both sets.

The trailer also doesn't forget to have some classic Sherlock banter to remind viewers of the tone that the series always had. The trailer ends with Sherlock talking to his older brother Mycroft ("Keep me informed," "Of what?" "Absolutely no idea.")

Sherlock and Watson (Martin Freeman) return in BBC's "Sherlock" season 4, which premieres next year.