Sherlock Season 4 trailer from Comic-Con! Something’s coming… Get your first look at Sherlock Season 4, starring Benedict Cumberbatch and Martin Freeman, coming to MASTERPIECE on PBS in 2017. Promising laughter, tears, shocks, surprises and extraordinary cases, it was announced previously that series four will begin – with the nation’s favourite detective, the mercurial Sherlock Holmes, back once more on British soil – as Doctor Watson and his wife, Mary, prepare for their biggest ever challenge – becoming parents for the first time. Sherlock: The Abominable Bride was the most watched program over the festive season with 11.6 million viewers and the highest-ever audience share for a Sherlock episode.