THE first trailer for season 4 of British mystery drama "Sherlock Holmes" has been unveiled at Comic-Con reports Deadline.

Teasing that "something's coming," it looks as though fans are in for an intense and suspense-filled fourth season of the hit BBC show.

With the trailer promising that "everything they know will be tested," "Sherlock" actor Benedict Cumberbatch along with co-star Amanda Abbington and co-creator Mark Gatis all agreed onstage at the event that the upcoming season would be the darkest yet.

When questioned on a fifth season, Cumberbatch agreed to return to the show for not only a season 5 but also seasons 6 and 7.

Although nothing was confirmed, Gatis did joke, "We can exclusively reveal that there won't be a fifth season ... but there will be a sixth."

The trailer can be viewed now on YouTube: https://www.youtube.com/watch?v=qlcWFoNqZHc