"Sherlock" fanatics have been warned: tear-jerk moments are ahead for the BBC series.

The series' co-creator Mark Gatiss has indicated that the fourth season of the series will be something like an adventurous tragedy.

"You can always expect tragedy as well as adventure, that's just how it goes," Mark Gatiss told RadioTimes.com.

Nonetheless, Gatiss has been quiet about whether that tragedy refers to the death of Doctor John Watson's wife Mary Watson, who is played by Martin Freeman's real-life partner Amanda Abbington. Freeman, himself, has made mention of the fact that Abbington's character will be killed off "at some point." After all that's what transpires 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 in the year. "So [John] gets married, and then Mary dies -- so at some point presumably she'll die."

However, Gatiss insisted that viewers should assume nothing, stating, "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.

"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."

Co-creator Steven Moffat and Gatiss have made painstaking efforts to select interesting moments from a variety of Sherlock Holmes' adventures, combining those independent elements to recreate Doyle's works, all-the-while adding unique flourishes and twists. That said, there is a road map that the creators adhere to, which Freeman has indicated in the past.  

But, Abbington's character has already outlived the literary version of herself, who died from natural causes sometime after Holmes' demise at Reichenbach Falls and before he returned three years later.

Abbington's Mary, who's a former assassin, will likely die in a much more spectacular way. While sad, Mary's death will inspire a sense of kinship between John Watson and Sherlock, and they will once again room together in their Baker Street apartment.

"Sherlock" will appear on BBC for a special that is expected to air in late 2015, and the full fourth season will air 2016.