 " The Empty Hearse " , written by Mark Gatiss and directed by Jeremy Lovering , is the first episode of Series 3 and was first broadcast on 1 January 2014 . Inspired by " The Adventure of the Empty House " by Sir Arthur Conan Doyle , the episode follows Sherlock Holmes ' return to London and reunion with John Watson , and their subsequent solving of an underground terrorist network . The episode achieved an official rating of 12 @.@ 72 million viewers , making it the highest rated drama episode shown on UK television in 2014 . 
