'Sherlock' Season 4 Spoilers, Air Date and Updates: Releases New Trailer for Next Season

A newly released trailer for "Sherlock" Season 4 hints the viewers of the TV series to what looks like a grim and dark season coming next year. The detective show will offer more exciting storylines to its viewers.

Season 4's first episode is named "The Six Thatchers" which is said to be in reference to a former prime minister in the United Kingdom. The second episode's title was also released to the public and will take the name "The Lying Detective." There is a hint that the series may be adapting Arthur Conan Doyle's tale 'The Dying Detective'.

The more than 1 minute teaser uploaded on YouTube showed that there will be a lot more threats and challenges waiting for Watson and Holmes. A dark storyline is also expected from the footage cuts of the trailers showing action-packed scenes.

A catching dialogue on the footage echoed a voice that said "Something's coming. Maybe it's Moriarty. Maybe it's not." It is believed that this could refer to a new villain coming to the show. Others think this is in reference to Culverton Smith's threat, according to Independent.

Holmes, on the other hand, was shown trying to convince the others that he has a rare disease which is deadly. This is in hopes of having Smith that he was the one behind the murder of the former's nephew.

Since it will be "Sherlock's" fourth and final season, many are convinced that the show will already give its best. Benedict Cumberbatch has earlier hinted about the end of the series saying it feels like "the end of an era" for him.

The fourth season of "Sherlock" will air on BBC One (UK) and PBS (US) beginning January 1. The new season will only have three episodes.