'Sherlock' Season 4 Teaser Puts Benedict Cumberbatch And Martin Freeman In Hot Water

Excluding 2016's Victorian-era special episode, it's been nearly three years since a proper episode of Sherlock has aired. But we're in the final stretch now, with the season four premiere set to air on BBC in the U.K. and on PBS in the United States on January 1, 2017. To remind you that the show's return is right around the corner, a mysterious new teaser trailer has arrived.

There is no actual footage from the new season in the trailer, just the strange image of Benedict Cumberbatch's Sherlock Holmes and Martin Freeman's John Watson chilling out in the former's flat...which has inexplicably begun to fill up with water. The imagery tells you everything you need to know – things are about to get very bad for these two.

Series creators Steven Moffat and Mark Gatiss have said that season four would be darker than usual and that Toby Jones' new villain is the nastiest adversary Holmes and Watson have faced yet. As Moffat explained in an interview with Collider:

He's completely different. It's a completely different character. He's the darkest villain we've had. There was always something charming and engaging about Moriarty. There was something fascinating and actually amoral, rather than immoral, about Charles Augustus Magnussen. This guy is the purest evil. Sherlock is actually appalled by him. He's the most evil villain we've had. I don't think that when you see it, you will disagree. He's horrific.

For the record, Jones is playing Culverton Smith, an antagonist in the Sir Arthur Conan Doyle story "The Adventure of the Dying Detective," one of the final Sherlock Holmes stories. Like past episodes of Sherlock, the series will probably use that tale as a jumping-off point to try something completely different.

This dark tone was also on full display in an earlier trailer, which suggests that everything bad that can possibly happen to Sherlock is about to happen this season.

With all this talk of darkness, I only hope the new season finds at least some moments of levity. This show's greatest strength has always been the chemistry between Cumberbatch and Freeman, who bounce off one another so effectively. With both actors in such high demand (they're both off making Marvel movies and such!), it's going to be a few more years before we can even start thinking about the fifth season and it 'd be good if the new season isn't built entirely out of misery.