 A fourth series has been commissioned , with scripts planned . Moffat told The Telegraph , " we 're all keen to continue , " but it has been difficult to co @-@ ordinate the lead actors ' schedules . Moffat continued , " And obviously Mark [ Gatiss ] and I have our other commitments too , but it 's just a matter of scheduling . " In July 2014 the BBC announced that filming for the series would take place in late 2015 , but Moffat announced in May 2015 that filming would not begin until April 2016 , with the series not expected to air until 2017 . Filming began on 4 April 2016 , scheduled to last until early August . In May 2016 it was announced that Toby Jones had been cast as a villain from Sherlock Holmes lore . 
