 The second series concluded with " The Reichenbach Fall " . Steve Thompson wrote the episode , which was directed by Toby Haynes , who had previously directed many of Moffat 's Doctor Who episodes . First broadcast on 15 January 2012 , the episode follows Moriarty 's plot to discredit and kill Sherlock Holmes , concluding with Holmes faking his suicide . It was based upon Conan Doyle 's story " The Final Problem " , in which Sherlock and Moriarty are presumed to have fallen to their deaths from the Reichenbach Falls in Switzerland . Moffat felt that he and co @-@ creator Gatiss had outdone Conan Doyle in their version of Holmes ' fall and Moffat added that , in that much @-@ discussed sequence , there was still " a clue everybody 's missed " . 
