‘Sherlock’ Season 4 Air Date, Spoilers, News & Updates: All Hell Breaks Loose For Sherlock, John And Mary

"Sherlock" Season 4 has already begun production in preparation for its expected release in 2017. Co-creator Mark Gatiss recently shared a sneak peek of Benedict Cumberbatch and Martin Freeman's return on the set of the BBC series. What can fans expect from Sherlock, John and Mary in series four?

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"Sherlock" Season 4 co-creator Mark Gatiss recently shared photos on the set of the BBC series, which showed Benedict Cumberbatch and Martin Freeman's return, reports Carter Matt. While the showrunner's teaser photos did not reveal much about the upcoming season, many fans are already speculating on the death of one of its characters - Mary Watson.

Back! #Sherlock pic.twitter.com/WFvpGpy3PV

— Mark Gatiss (@Markgatiss) April 11, 2016

Den of Geek notes that "Sherlock" Season 4 will be less light-hearted compared to Season 3. In an earlier interview with Gatiss, he revealed that the upcoming season will see Sherlock, John and Mary go through something difficult together.

"Even though Mary is very proactive and a huge part, it's a sort of breathing space between 'Vow' and the next one," he said.

Many fans have begun speculating that Mary will be dying from childbirth in "Sherlock" Season 4. The official synopsis also does not reveal much about the upcoming season of the BBC series, but it does hint that some of the focus will be dealing with John and Mary's preparation for parenthood.

"[Season 4] begins with the nation's favorite detective, the mercurial Sherlock Holmes, back once more on British soil, as Doctor Watson and his wife Mary prepare for their biggest ever challenge - becoming parents for the first time," the official synopsis stated.

There are also rumors that "Sherlock" Season 4 will be its series finale, as Gatiss and Steven Moffat previously hinted that the show is "about to reach its climax." Add this to the fact that Benedict Cumberbatch and Martin Freeman have a lot of projects to do on their schedule.

"Sherlock" Season 4 is expected to premiere in January 2017 on BBC.