Sherlock goes to a dark place for the season 4 teaser trailer

The first teaser trailer for season 4 of Sherlock has been released at San Diego Comic Con and it hints at a much darker storyline for the high-functioning sociopath/detective and his friends. Watch it below:

As with the final moments of season 3, Moriarty makes an appearance here, but in true teaser-style we still don't know whether he's actually returned from the dead or not. We do know that things don't look great for Sherlock though. 

"Everything they know will be tested. Everyone they know is under threat," the trailer reads. Pair this with images of Martin Freeman standing over a hospital bed and Benedict Cumberbatch looking traumatised in a morgue, and I think it's safe to say we're in for a much darker Sherlock next year. 

This is something which was supported by the Sherlock panel at SDCC. "It’s really dark." Said Amanda Abbington, who plays Watson's wife Mary in the show. "It's the darkest that Steven [Moffat] and Mark [Gatiss] have written." Benedict Cumberbatch agreed, adding: "There’s a genuine emotional roller coster this series, and the learning curves are massive."

Sherlock season 4 will premiere in 2017.

Images: BBC