Mary Watson (Amanda Abbington) may end up dying when BBC's hit series "Sherlock" returns for its fourth season sometime in 2017.

Co-creator Stephen Moffat's revelation during the Comic-Con back in July that they were planning to "up the ante" for the upcoming installment seemingly bespoke of a tragedy that would befall the main characters.

"We know very, very clearly what stories we're doing. Where each episode goes, what the shattering, emotionally draining, you'll never be the same again and you'll never stop crying cliffhangers will be," said Moffat.

Movie Pilot posits that this sad plot has something to do with John's (Martin Freeman) wife, Mary. In the Arthur Conan Doyle book, Mrs. Watson was last seen after getting married to the doctor. It appeared that she died shortly after the union, leaving her husband a widower.

In an interview with Telegraph, Freeman shared that he would not be surprised if Mary ends up dying in the series, as the writers mostly abide by Doyle's novel.

According to Freeman, "While we play fast and loose with the original stories, we generally follow the trajectory of what Conan Doyle did. So John gets married, and then Mary dies — so at some point presumably she'll die."

Meanwhile, Entertainment Weekly reveals that the special episode of "Sherlock" set for Christmas will take back fans to the era where the British author based his stories. Moffat said that Holmes (Benedict Cumberbatch) and Watson will be going old school, as they sport original period costumes.

The showrunner also said that Cumberbatch's character will be a lot "nicer" as a person and will not behave like his "usual sarcastic self." The epoch will reportedly dictate that Holmes be "a proper polished Victorian gentleman." Moffatt shared that the actor was happy with the idea of not being "a brat" for a change.

The "Sherlock" special episode is slated to air Christmas of 2015. As for season 4, filming is said to start next year, with the series expected to be released in 2017.