SherlockThe night is dark and full of terrors on "Sherlock."

Season 4 of the show promises to be its darkest yet. And a recently-released portrait image of Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as John Watson indicate troubled times ahead for the partners in crime-solving.

The men are dressed in dark tones, set against a dark backround. As Sherlock peers skeptically at the camera, eyebrow quirked, Watson gazes off to the side. Maybe he's on the lookout for some unknown danger? Or is he just he fed up with his BFF's usual, persnickety ways?
Who knows, because the creators have revealed very little about season 4. At Comic Con, Steven Moffat did say "it is explicitly a darker season." And that the new villain played by Toby Jones is the worst. " This guy is the purest evil," Moffat said. "Sherlock is actually appalled by him. He's the most evil villain we've had."

"Sherlock" season 4 is expected to air sometime in 2017.

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