The first episode, A Study in Pink, was first aired on 25 July 2010, written by Steven Moffat and directed by Paul McGuigan. Roughly based on the Sir Arthur Conan Doyle story A Study in Scarlet, the episode introduces the consulting detective Sherlock Holmes with his companion John Watson and their adventure hunting down a serial killer in London.
The Blind Banker, written by Stephen Thompson and directed by Euros Lyn, first aired on 1 August 2010. The episode tells Sherlock and John's adventure as they are approached by an acquaintance of Sherlock's to investigate mysterious graffiti.
The last episode of the first season, The Great Game, was written by Mark Gatiss and directed by McGuigan. First aired on 8 August 2010, the episode introduced the consulting criminal Jim Moriarty, who ensnares Sherlock with a series of complex challenges. The episode ends on a cliffhanger, with Sherlock holding Jim at gunpoint.
- Many Happy Returns (mini-episode)