Los Angeles: Fans of the Emmy-winning TV series "Sherlock" have a reason to rejoice, as a new trailer for the fourth season of the show is here with a promise that "everything they know will be tested".

Fans at the British mystery show's Comic-Con panel were treated to the first trailer for the fourth series here. Stars Benedict Cumberbatch and Amanda Abbington, co-creators Steven Moffat and Mark Gatiss and producer Sue Vertue were present.

The new look seemed to be more action-filled than past instalments, and intoned that "Something's coming. Maybe it's Moriarty, maybe it's not. But something's coming", reports variety.com.

Cumberbatch returns as Detective Sherlock Holmes, joined by his best friend Dr. John Watson, played by Martin Freeman.

The show last left off with Andrew Scott's villainous Moriarty seemingly coming back to life after shooting himself in the face.

Holmes, however, figured out in the 2016 Christmas special, "The Abominable Bride", that Moriarty is in fact dead -- but that doesn't mean that the criminal mastermind doesn't pose a threat.

Complicating matters is the fact that Toby Jones will be joining the show as another one of Arthur Conan Doyle's villains. Holmes and Watson will have to face problems with both bad guys, which, as the new trailer shows, will be a challenging feat even for them.

"Sherlock" will return to the BBC in 2017. IANS