Benedict Cumberbatch can currently be seen on the big screen playing Stephen Vincent Strange in Marvel Studios' sorcerer adventure, Doctor Strange. The lauded actor will (very) soon return to the role that made him a fan-favorite in the first place, when the long-awaited Sherlock season 4 airs. The marketing push has picked up for this next season of Sherlock of late too, what with the first episode of the modern-day Sherlock Holmes TV series' fourth season - titled 'The Six Thatchers' - being officially scheduled to air at the literal beginning of the new year, in 2017.
Sherlock season 4 will, among other things, see John (Martin Freeman) and Mary Watson (Amanda Abbington) add a new member to their family; Sherlock (Cumberbatch) attempt to uncover the truth behind the mysterious message that he received from the late Moriarty in the Sherlock season 3 finale (something he spent the Sherlock Christmas special, 'The Abominable Bride', puzzling over); and Sherlock, John and their allies face off with Culverton Smith (Toby Jones), a fellow who promises to be our heroes' worst nightmare.
Based on the trailers and promos released so far, it appears as though Sherlock co-creators Mark Gatiss and Steven Moffat are making good on their promise to take the show into darker territory in season 4. The second proper trailer released for Sherlock season 4 (see above) further supports that claim, by featuring ominous imagery and foreboding clips from the season - among them, a moment in which Culveton Smith appears to suggest that he wants to make Sherlock do the worst thing imaginable to his closest friends: "Tell them your darkest secret."
Sherlock season 4 is shaping up to be a game-changer for the series as a whole. This isn't something that its cast and crew have denied either, with Cumberbatch having said that the show could continue on in a fifth season - but that the series "will not happen again in the same regularity," due to what transpires during the season 4 finale in particular. The final episode of Sherlock season 4 is titled "The Final Problem", further supporting the notion that things will not ever be the same again in the Sherlock-verse after that chapter in Sherlock and John's story.
The second trailer for Sherlock season 4 doesn't offer much in the way of clues about what to expect when the show returns, either. If anything, the preview raises more questions than its answers, with out of context scenes that include Sherlock and John looking more concerned than usual; Mycroft Holmes (Gatiss) commenting on Sherlock's "demons"; and most intriguingly, the brief moment in which Sherlock says "I love you" for reasons (and to someone) that remain unknown for now. Seeing as this could potentially be the final season of Sherlock, it's encouraging to see that it's cast and crew are taking steps to make sure that the series goes out with a bang.
Sherlock returns with 'The Six Thatchers' on BBC1 in the U.K. and PBS in the U.S., on January 1st, 2017.