Watch the Season 4 trailer for BBC's Sherlock

A new game is afoot: The first trailer BBC's Sherlock Season 4 has been released following a busy weekend at San Diego Comic Con.

It's been a long-time coming, but fans of BBC's Sherlock have finally been given the first official trailer for the series' next season. News broke that Sherlock would be receiving a fourth season earlier this year when PBS President Paula Kerger announced the development. She said that the show's shooting schedule would be somewhat delayed due to Benedict Cumberbatch's growing popularity but that the series would be returning.

And, judging from this newest trailer, it looks like the return has been worth all of our waits. The teaser begins with a static image of Jim Moriarty from the third season's finale as the sociopathic villain asks, "Did you miss me?" The scene then switches to Sherlock who appears to be sitting inside 221B Baker Street. A voice-over can be heard of the detective saying, "Something is coming. Maybe it's Moriarty, maybe it's not."

The trailer then kicks it into high gear as fans are reintroduced to many much-missed (and familiar!) faces. From Molly Hooper to Mrs. Hudson, fans can see that the next season's unknown threat has placed all of Sherlock's acquaintances in peril. Even the often demure Hooper is seen crying out to Sherlock, telling the man that this "is not a game."

Fans are also treated to some new faces, particularly that of the series' newest baddie. Toby Jones (Captain America films) joined the Sherlock squad to play Culverton Smith, a well-known villain from Sir Arthur Conan Doyle's titular novels.

The video teases that "Everything they know will be tested. Everyone they know is under threat." Clearly, Sherlock is heading for some serious drama next season as all of the series' characters band together against a new (or perhaps old?) threat. Even Sherlock and Watson appear to be overwhelmed by the ever-present danger, and even Mrs. Hudson is seen turning against Sherlock's shifty brother Mycroft when she seethes, "Get out of my house, you reptile." Get it, Mrs. Hudson. It's about time somebody brought down the 'government official' a peg or twelve.

Currently, there's no official release date for when Sherlock Season 4 will hit TV in the UK or abroad, but fans are expecting its newest episodes to air at the start of 2017.