"Sherlock" co-creator Mark Gatiss hinted that the plot or the story on which the new season of the series will be based is still undecided.

Gatiss revealed to Radio Times that the people behind the series want season 4 to be at par with season 3, adding that instead of introducing a new antagonist like Charles Magnussen, they are looking for a story that is parallel to the previous season.

"It is a series about a detective, it is not a detective series," Gatiss said.

Show co-creator and writer Steven Moffat and executive producer Sue Vertue are in agreement.

"The show has to keep evolving, it has to move on at a pace, I think," Vertue said.

These statements from the creators and executive producers of the series are in line with their previous proclamations, saying that the fourth season of the hit crime drama "Sherlock" will exceed fans' expectations. Reports stated that the new season will be darker and more devastating than the previous seasons.

Moffat previously said that the characters of the series will be taken to another place. He assured that the crew behind the series has a lot of ideas for next season. He also said that season 4 will top the third season of the series. There are a lot of speculations how the fourth season will top the previous season like creating a big twist in the story by bringing back the vicious antagonist Moriarty.

As the show reaped a number of Emmy awards, "Sherlock" season 4 will surely return to BBC in early 2016 with no official date yet. However, the series will also hold a Christmas special planned for December 2015 and will be based on the mystery "The Adventure of the Blue Carbuncle."