"The roads we walk have demons beneath, and yours have been waiting for a very long time..."

That darkness the cast and crew of Sherlock have hinted at is there in spades in the new trailer for series four. Burning buildings, guns, John (at least we're pretty sure it's John) trapped down a well and an appearance from disturbing new villain Culverton Smith (Toby Jones), who seems to have Sherlock right where he wants him.

Hopefully the next trailer will have some of the laughs we were also promised...

Sherlock series four begins with The Six Thatchers on New Year's Day at 8:30pm on BBC1