Sherlock Series 4: Filming Update on Christmas Special Episode

Looks like Sherlock Season 4 will have its fair share of tragedies. Fans can expect some tear-jerking moments in the upcoming episodes of the popular British TV series, according to the show's co-creator Mark Gatiss.

"Expect tragedy as well as adventure, that's just how it goes," Gatiss told Radio Times.

According to a report by The Independent, one character who could be killed off in the upcoming season is John Watson's wife Mary, played by Amanda Abbington, real-life partner of Watson actor Martin Freeman.

Freeman has previously suggested that Mary could be killed off "at some point" in line with Conan Doyle's stories.

"While we play fast and loose with the original stories, we generally follow the trajectory of what Conan Doyle did," he told The Telegraph. "So [Watson] gets married and then Mary dies – so at some point presumably she'll die."

However, Gatiss doesn't want viewers to jump to conclusions just yet. As per him, the TV show's plotline would not necessarily follow that of Sir Arthur Conan Doyle's original books.

"Just because it's in the stories, doesn't mean it'll happen in the series," he said. "There's an awful lot of changes and an awful lot of places to go and things to do.

"It should be clear by now that while, of course, Doyle is our absolute god, we have gone quite a long way away as well. We've introduced Sherlock and Mycroft's parents – I don't think they've ever been seen in any adaptation – so there are lots of surprises to come."

Production on a one-off Sherlock special begins in January, 2015 for a possible Christmas broadcast while an additional three episodes will be shot later in the year to be aired in 2016.