'Sherlock' season 4 plot, release date: Mary Sue to die? No 'Doctor Who' crossover

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The special episode of "Sherlock," which aired early last month, was well received by fans, who now can't wait to find out what happens next in the series.

The answers won't come until at least next year, since filming of season 4 will start this spring. While it's going to be a long wait, series co-creator Mark Gatiss somehow provided some bits of information for fans to feast on.

Speaking to RadioTimes, Gatiss teased that fans are in for some tragic storylines. "You can always expect tragedy as well as adventure, that's just how it goes," he told the publication.

Although Gatiss did not reveal what the tragedy is about, speculations suggest that John Watson's (Martin Freeman) wife, Mary (Amanda Abbington) may die. This story was suggested by Freeman himself, when he revealed that "at some point," Mary will die just like how she did in Sir Arthur Conan Doyle's stories.

Gatiss also shared that they don't really stray far from the original stories and they have followed what Conan Doyle did with the story. Still, the co-creator advised fans not to jump into conclusions.

"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," Gatiss explained.

"Sherlock" season 4 is bound to bring viewers surprises and it's guaranteed to keep them hooked, as promised by producer Steven Moffat in an interview last year with Entertainment Weekly.

When asked about how fans will feel after watching the brand new season, Moffat replied, "Hmmm... desperate for series 5. We're certainly going to put them through the mill."

Meanwhile, fans had also hoped that "Sherlock" would have a crossover with "Doctor Who." But Gatiss already shot down rumors and told Entertainment Weekly in December last year that a crossover between two shows will only happen "over my dead body."

"Sherlock" is expected to return with season 4 in January 2017.