Benedict Cumberbatch
Benedict CumberbatchReuters

When "Sherlock" finally returns with its fourth season, fans will have to brace themselves for a tragedy, which might befall a beloved character.

Filming of season 4 is said to begin sometime in early 2015, with a premiere date expected in early 2016. However, no specified dates have been set yet, much to the disappointment of fans of the series starring Benedict Cumberbatch as Sherlock and Martin Freeman as John Watson.

Season 4 spoilers have been doing the rounds since the previous season ended early this year, and the death of a beloved character was speculated back then as well. And series co-creator Mark Gatiss confirmed it when he told that "you can always expect tragedy as well as adventure, that's just how it goes."

However, Gatiss wouldn't confirm if the tragedy is the death of Watson's wife Mary, played by Freeman's real-life partner Amanda Abbington.

It wasn't long back that Freeman himself suggested that Mary will be killed off "at some point", as depicted in Sir Arthur Conan Doyle's Sherlock Holmes stories.

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

But Gatiss warns viewers from jumping into any conclusions based on Freeman's predictions.

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

"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 [for instance], I don't think they've ever been seen in any adaptation – so there are lots of surprises to come."

Mary was well into her last trimester when Season 3's final episode aired, and it is safe to assume that Watson and Mary will be shown as new parents when the upcoming season airs. And they will indeed make interesting parents, Abbington told Vulture in an interview.

"On the one hand, they'd probably be reckless because they're both quite psychopathic," said Abbington. "But I think an assassin and an army doctor who loves trouble, I mean, that kid has got nothing to worry about. Screwed up mentally, of course, but if there's any bullying on the playground, we're covered."