Watch the dark trailer for the fourth season of Sherlock
A first trailer for the hugely anticipated fourth season of Sherlock has been unveiled. Click below to watch it.
The preview is a short one, but very dark in tone and sees Benedict Cumberbatch's Sherlock and Martin Freeman's Watson facing their most difficult challenge yet.
Toby Jones will play the series' key villain, though it's unknown what role he will be playing as yet.