On Jan. 8, "Sherlock" Season 4 took a major turn when its second episode made its debut. In the episode, Sherlock found himself in a risky game with his friend and sidekick Dr. John Watson and brother Mycroft. With the true identity of another mysterious character brought to light, the episode left fans wondering how the consulting detective's story will come to a close.
When the Season 4 finale titled "The Final Problem" airs, fans will find both Sherlock and Watson in another edgy situation, Comicbook reported. The trailer for the upcoming episode suggests that the situation of the two will be something far more than a dangerous game.
In the clip, Sherlock appears to be on the verge of tearing up. Mycroft can be heard telling his brother, "Every choice you've ever made, every path you've ever take--the man you are today is your memory of Eurus."
Watson then tells Sherlock that despite things being difficult for him, he has to keep it together. It looks like the two men are both referring to the major shocker that left fans gasping in the previous episode, titled "The Lying Detective."
It can be recalled that in the final moments of episode 2, it was revealed that Sherlock actually had a sister named Eurus, who happens to be just as shrewd as Sherlock and Mycroft. The character first made an appearance when she had an affair with John. Eventually, she disguised herself as a flirty bus passenger, a serial killer's daughter and John's new therapist.
It also seemed to have turned out that Moriarty was not the mysterious one behind the posthumous "Miss Me?" messages, but Eurus, Screen Crush noted. Although she invoked the message in an invisible ink message to her detective brother, it remains unknown if she was also the one behind the first Moriarty message. In any case, the official synopsis for the Season 4 finale reveals that Sherlock's newfound sister will be his greatest challenge yet.
The Season 4 finale will see the return of Benedict Cumberbatch as Sherlock, Martin Freeman as John Watson, Mark Gatiss as Mycroft, Amanda Abington as Mary Watson, Una Stubbs as Mrs. Hudson, Rupert Graves as Inspector Lestrade and Louise Brealey as Molly Hooper. "The Final Problem" airs on Jan. 15 on BBC.
Watch "Sherlock" Season 4, episode 3 trailer here: