'Sherlock' Season 4 Air Date, Cast, News & Updates: Did Holmes Just Reveal His Darkest SECRET?

"Sherlock Season 4" from the BBC, which stars Benedict Cumberbatch (Holmes) and Martin Freeman (Dr. John Watson), alluded to a very dark secret in its recent trailer. Season 4 villain Culverton Smith (Toby Jones) posed a challenge to the series lead. As the trailer teased, Sherlock's secret has to do with his brother Mycroft Holmes (Mark Gatiss) and best friend John Watson.

Digital Trends cites Culverton Smith as one of the most difficult enemies for Sherlock to have. Based on the new Season 4 trailer released by the BBC, Culverton Smith seems to have gotten under Sherlock Holmes' skin. In the BBC trailer, Culverton Smith told Holmes that the worst thing to do to one's dearest friends is to tell them him darkest secret.

The trailer then switched to a very distressed looking Sherlock. Behind him stood Mycroft Holmes and John Watson. The BBC series star then uttered the three words he has never been heard telling anyone - "I love you."

Congratulations to the new parents… pic.twitter.com/qJxMHRVwIE

— Sherlock (@Sherlock221B) December 12, 2016

Was this Sherlock's darkest secret? That despite his outward clumsiness, distance and social dysfunction, an enemy can get to him by way of those he loved the most: Mycroft Holmes and John Watson? The media outlet points out at that Season 4 seems very dark indeed and the new trailer conveyed this quite effectively.

Radio Times cites that "Sherlock Season 4" will air on the BBC in the UK and PBS in the US as follows: Ep 1 "The Six Thatchers" on Jan 1; Ep 2 "The Lying Detective" on Jan 8; and Ep 3 "The Final Problem" on Jan 15. Following the Season 4 finale, the BBC series is believed to be going on a long hiatus. At the moment, this is the more optimistic stance as both cast and showrunners of the BBC series have yet to announce full confirm on "Sherlock Season 5."