"Sherlock" season 4 teases of "consequences" of Sherlock's deepest darkest secret possibly involving the third Holmes brother and John's refusal to face Mary's past. "Sherlock" trailers reveal a darker series that hints loudly of an impending death possibly of one of the main characters, possibly Mary or Mycroft or could even be both. However, the darker series provides Benedict Cumberbatch acting challenges that may entice the actor to stay on.

"Sherlock" season 4 episode 1, "The Six Thatchers," will be coming in January 1, 2017, a few days more to go and yet fans are still making speculations extracting bits of information on released "Sherlock" trailers. The first trailer hinted of consequences of past actions, may be referring to a transgression committed by Sherlock and which has become his deepest darkest secret.

This secret may involve the long-lost third Holmes brother, Sherrinford, who will most likely make an appearance in "Sherlock" season 4 as hinted by co-creator Mark Gatiss in the recent comic-con. Moreover, rumors say that Sherlock may have something to do with the burning house and the estrangement of Sherrinford from the Holmes family.

There will also be consequences that John Watson has to face for refusing to know about his wife Mary's past as an assassin, Digital Spy has learned. Mary's wrongdoings may haunt them and may even put baby Watson in dire danger.

Speculations point to these consequences as more villainous than Culverton Smith played by Toby Jones, the new arch-enemy for "Sherlock" season 4. Gatiss in speaking to Entertainment Weekly has declared that both Sherlock and John will suffer an emotional upheaval in "Sherlock" season 4, meaning that an impending death is looming. This death could only be either Mary or Mycroft, being the closest to both John and Sherlock.

Meanwhile, the dark "Sherlock" season 4 is providing acting challenges to Cumberbatch, enticing him to stay on playing Sherlock for more seasons. Cumberbatch recently corrected rumors that he stated that the series will be his last for in truth he only meant the last filming for the series until pre-production is completed for season 5.