It's been less than 24 hours since RadioTimes.com published their interview with Mark Gatiss hinting that "tragedy" will strike on Season 4 of "Sherlock," but fans are already worrying about which fan-favorite character might kick the bucket.  

On Thursday, Gatiss told Radio Times that fans "can always expect tragedy as well as adventure."

"That's just how it goes," he added.

While it's not clear if a character will be killed, Gatiss previously hinted at Mary's (Amanda Abbington) demise.   

"While we play fast and loose with the original stories, we generally follow the trajectory of what Conan Doyle did," he said in a June interview with the British Telegraph. "So [John] gets married, and then Mary dies - so at some point presumably she'll die."

Gatiss then added, "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... so there are lots of surprises to come."

Well, if you check Twitter fans have already started theorizing on what that "tragedy" could be. Some believe Mary will be killed, while others worry something may happen to her baby. There was even an idea that Mycroft Holmes (Gatiss) will get the ax.

"Just a guess: The 'tragedy' in S4 of Sherlock is going to involve either Mary or her baby or both of them #isthatjumpingshark?" @robin_rdbrst tweeted.

"Sherlock's co-creator warns fans about a tragedy. Mary is gonna die. Duh! #BookReader #SpoilerAlert #Sherlocked," @rahzAriaM wrote.

"I guess the 'tragedy' in Sherlock s4 is character's death. Possibly Mary or Mycroft," @Cassie4more posted.

According to Variety, a special episode for Season 4 of "Sherlock" will begin filming in January and the three-episode season begins shooting later that year. The series stars Benedict Cumberbatch as Sherlock and Martin Freeman as John Watson.

What do you think the "tragedy" means?