It's been three years since we've last had a proper season of Sherlock, but the wait is almost over.
Sherlock last left off with the detective's archenemy Moriarty (Andrew Scott) taunting Holmes from beyond the grave when a video of the villain began broadcasting all across England. While we don't know who was behind Moriarty's posthumous plot, there is plenty we do know about Season 4.
1. Episode 1 is likely inspired by The Six Napoleons
The premiere's title, "The Six Thatchers," is a clear reference to the Sir Arthur Conan Doyle story "The Six Napoleons," in which Holmes is enlisted to track down a man who shatters busts of Napoleon and soon escalates to murder.
In 2011, Watson's blog already chronicled the story of "The Six Thatchers," in which a murderer smashes pottery figures of Margaret Thatcher. But as of now, it's unknown just how closely the series will resemble the blog or original tale.
2. Episode 2 is likely inspired by The Dying Detective
The second episode's title, "The Lying Detective," once again bears a striking similarity to a Conan Doyle story. This time, it appears to be paying homage to "The Dying Detective," in which Sherlock is dying of a rare disease and Watson is called to tend on him.
3. Toby Jones will play the villain
Jones will play one of Conan Doyle's most devious villains, Culverton Smith, who plays a pivotal role in "The Lying Detective." We don't want to give too much away about Smith or how he's tied to Sherlock's mortal illness, but trust us when we say you're in for more than a few twists.
4. Episode 3 will get a special theatrical release
Titled "The Final Problem," the season's final episode with screen in movie theaters on Jan. 16 and Jan. 18. The event will take place in approximately 350 movie theaters across the country and the big screen broadcast will include 15 minutes of bonus footage. So if you're a serious Sherlock fan, this is an opportunity you won't want to miss. See if it's coming to a theater near you right here!
5. Mary might die
Fans of Conan Doyle's books know that Watson's wife Mary (Amanda Abbington) dies at some point after they marry -- something Freeman hinted will happen in the show, as well, during an interview last year. "While we play fast and loose with the original stories, we generally follow the trajectory of what Conan Doyle did. So he [Watson] gets married, and then Mary dies -- so at some point presumably she'll die," Freeman said.
We know Mary at least lives long enough to give birth to her and Watson's child, but all bets are off after that.
6. Sherlock grows some stubble
In a photo from the set, Sherlock looks uncharacteristically unkempt. Most likely, this photo is from "The Lying Detective," when Sherlock has fallen ill. And although it can't compare to John's mustache, we're glad to see some more facial hair this season.
7. It might finally introduced the third Holmes brother
At San Diego Comic-Con, the panelists teased three names that would be crucial to Season 4: Thatcher, Smith and Sherrinford. Since Thatcher and Smith correspond to Episode 1 and 2, respectively, it's fair to assume that Sherrinford will correspond to Episode 3, prompting many fans to assume the finale will reveal the mysterious third Holmes brother.
Sherrinford was a name Conan Doyle once considered for the character Sherlock, and Mycroft has previously referred to their "other" brother. And thanks to some expert-level trolling by co-creator and Mycroft actor Mark Gatiss, some fans are now convinced Tom Hiddleston will be playing the third Holmes.
At Comic-Con, Gatiss teased that they may have had Hiddleston on Sherlock already. Adding fuel to the fire, Gatiss then tweeted a picture of himself, Hiddleston and Abbington captioned, "Blud," which is what Sherlock says to Mycroft in a rare moment of brotherly connection.
8. It may, or may not, be the final season
Cumberbatch sent fans into a panic when he seemingly discussed the end of the beloved series, saying this season "feels like the end of an era." However, showrunner Steven Moffat was quick to rebuke the rumors that Sherlock was ending.
"That's not what Benedict said. That's what someone edited his words into the meaning of," Moffat says. "He was quite specific about being keen to carry on. He went on to say he's hard to get us all together. We want to keep the quality up. We haven't even seen this [season air] yet. We don't know. We haven't sat down with the intent to anything yet."
And yet Cumberbatch's sentiments were also echoed by Freeman, who discussed the "finality" of Season 4 during a radio interview. "Life does sometimes have a way of telling you. 'This is probably it now.' This last [season] did have a feeling of... I don't know whether it has a finality to it, but certainly had a feeling of a pause," Freedman said. "And I am never, ever afraid of things ending. I mean I am not looking forward to life ending or love ending, but things that we make should end."
Sherlock returns Sunday, Jan. 1 on PBS.