• Actor Benedict Cumberbatch (L) and actor/writer/producer Mark Gatiss attend the 'Sherlock' panel during Comic-Con International 2016 at San Diego Convention Center on July 24, 2016 in San Diego, California.

Actor Benedict Cumberbatch (L) and actor/writer/producer Mark Gatiss attend the 'Sherlock' panel during Comic-Con International 2016 at San Diego Convention Center on July 24, 2016 in San Diego, California. (Photo : Getty Images/ Kevin Winter)

A lot of big changes are coming when "Sherlock" Season 4 returns in 2017. The famous detective drama is welcoming Baby Watson, the bundle of joy for new parents Dr. John (Martin Freeman) and Mary Watson (Amanda Abbington).

Although the baby adds a different element to the show, co-creator Mar Gatiss reiterated that the British TV series is not departing from its darker "Sherlock" Season 4. Viewers will find the next season a mixture of laughter and action.

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"It creates a different dynamic," co-creator Mark Gatiss told TVLine. "Now I must stress, although we have a lot of fun with it, it doesn't mean that Sherlock has become Two Men, a Woman and a Baby. But we do have fun with it, because there's fun to be had."

The villains of "Sherlock" Season 4 include Toby Jones, casts as Culverton Smith and Andrew Scott as Moriarty. Gatiss teased that the return of Moriarty is something that viewers have to watch out for. Scott's character had an early demise in Season 2.

Rumors are high that the upcoming run may be the show's last, but Gatiss remained mum on the issue. The Season 4 finale titled "The Final Problem" may see the departure of Sherlock Holmes (Benedict Cumberbatch) if the story will follow the Arthur Conan Doyle story.

If Cumberbatch will follow the path of Basil Rathbone for his Holmes portrayal, the former still has 14 years to go before wrapping up his role. Freeman, on the other hand, has 11 years to go until he reached Nigel Bruce's last portrayal of Watson. If this will be the basis, definitely, "Sherlock" Season 4 is not the final season yet.

Rathbone and Bruce teamed up for a total of 14 movies between 1939 and 1946. They glamorized the roles of Holmes and Watson, respectively during those years.

When it comes to the script of Season 4, co-creator Steven Moffat thinks that it is the best story that he had written so far. However, he still knows that the viewers are the only one who can really judge his work, Comic Book reported.

"Sherlock" Season 4 has three episodes "The Six Thatchers," "The Lying Detective" and "The Final Problem." "Sherlock" returns in the United States and in the United Kingdom on Jan. 1, 2017. 

Watch the second trailer of Season 4 here: