Created by Steven Moffat and Mark Gatiss, the show stars Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as Doctor John Watson.

Holmes is assisted in his mystery solving by his flatmate, friend and companion, Dr John Watson (Martin Freeman), who has returned from military service in Afghanistan with the Royal Army Medical Corps.

Although Metropolitan Police Service Detective Inspector Greg Lestrade (Rupert Graves) and others are suspicious of Holmes at first, over time, his exceptional intellect and bold powers of observation persuade them of his value.

Although the series depicts a variety of crimes and perpetrators, Holmes's conflict with his archenemy, Jim Moriarty (Andrew Scott), is a recurring feature.

Steven Moffat and Mark Gatiss, Sherlock Holmes fans with experience of adapting or using Victorian literature for television, devised the concept of the series.

[16] Gatiss has criticised recent television adaptations of the Conan Doyle stories as "too reverential and too slow", aiming instead to be as irreverent to the canon as the 1930s and 1940s films starring Basil Rathbone and Nigel Bruce, which were mostly set in the then-contemporary interwar era.

[24] According to Screen Rant and a PhD thesis from De Montfort University, Cumberbatch's Sherlock is more anti-social and cruel to people around him compared to Doyle's character, which makes him more disliked by policemen who use his services.

"[27] Piers Wenger, head of drama at BBC Cymru Wales, described the series's rendering of Sherlock as "a dynamic superhero in a modern world, an arrogant, genius sleuth driven by a desire to prove himself cleverer than the perpetrator and the police—everyone in fact".

[28] In an interview with The Observer, co-creator Mark Gatiss says that they experienced more difficulty finding the right actor to play Dr John Watson than they had for the title character.

"[34] The remainder of the regular cast includes Una Stubbs (who has known Cumberbatch since he was four years old, as she had worked with his mother Wanda Ventham)[35] as Mrs Hudson and co-creator Mark Gatiss as Mycroft Holmes.

[36] Vinette Robinson, Jonathan Aris and Louise Brealey play the recurring roles of Sergeant Sally Donovan, Philip Anderson and Molly Hooper, respectively.

Guest appearances included Phil Davis as Jefferson Hope,[37] Paul Chequer as DI Dimmock,[38] Zoe Telford as Sarah,[38] Gemma Chan as Soo Lin Yao,[38] John Sessions as Kenny Prince,[39] Haydn Gwynne as Miss Wenceslas,[39] Deborah Moore[34] as one of Moriarty's victims and Peter Davison as the voice-over in the planetarium.

[54] Sarah Arthur, the series's costume designer, explained how she achieved the detective's look: "Holmes wouldn't have any interest in fashion so I went for classic suits with a modern twist: narrow-leg trousers and a two-button, slim-cut jacket.

The story depicts the introduction of Sherlock to John, and them entering a flatshare at Baker Street in London, and then their investigation into a series of deaths, initially believed to be suicides.

Written by Stephen Thompson and directed by Euros Lyn, the episode depicts Holmes being hired by an old university acquaintance to investigate a mysterious break-in at a bank in the City of London.

Written by Mark Gatiss and directed by McGuigan, "The Great Game" ends with a cliffhanger in which Sherlock and Moriarty reach a standoff involving a bomb attached to a vest removed moments earlier from Watson.

Loosely based on "A Scandal in Bohemia", the episode depicts Holmes's quest to retrieve compromising photos of a minor royal held on the camera phone of Irene Adler (Lara Pulver), a ruthless and brilliant dominatrix who also trades in classified information extracted from her rich and powerful clients.

[80] The episode was inspired by Conan Doyle's story "The Final Problem", in which Holmes and Moriarty are presumed to have fallen to their deaths from the Reichenbach Falls in Switzerland.

Inspired by "The Adventure of the Empty House" by Sir Arthur Conan Doyle, the episode follows Sherlock Holmes's return to London and reunion with John Watson, and their subsequent solving of an underground terrorist network.

The final episode "His Last Vow" was first broadcast on 12 January 2014, on BBC One, and written by Steven Moffat, directed by Nick Hurran and is based on Sir Arthur Conan Doyle's "The Adventure of Charles Augustus Milverton".

[96] Exclusive bonus material in the cinema presentation included a guided tour of 221B Baker Street from Steven Moffat and a look behind the scenes at how the special episode was made featuring all the lead cast and crew.

[105] The incident would be referenced in the WARS Trading Card Game tie-in series Academy 27, where the short story Apple Tree Yard references the theory.

[27] Following the second series's opening episode, Sarah Crompton, for The Telegraph, asserts that "Cumberbatch is utterly credible as a man who lives entirely in his cerebellum with little regard for the world outside, mak[ing] Sherlock the perfect depiction of Holmes for our times".

Gwilym Mumford, for The Guardian, suggested that "this has to do with the fact that Moffat and Gatiss are enormously knowledgeable about Conan Doyle's work, and their reimagining incorporates big- and small-screen adaptations of Holmes, as well as the original stories.

[127] Commenting specifically on the second series's finale "The Reichenbach Fall", The Guardian's Sam Wollaston praised the show's faithfulness to Conan Doyle, but also how "it will wander, taking in mobile phone technology and computer hacking ...

[131] Aja Romano, writing for Vox about the fourth series, criticised the show as having "floundered", describing it as "indulging in cockamamie leaps of logic and inexplicable fantasies, with barely any character development to back them up".

Romano went on to ascribe the problems of the series to it "never [knowing] whether its current season would be its last" due to the rise to stardom of its main actors, and the show's "unearned love with itself" meaning that "plots never had enduring consequences".

[141][142] The series's conclusion, "The Reichenbach Fall", in which Sherlock fakes his suicide by jumping from St Bartholomew's Hospital, led to speculation on forums, social networking sites and in newspaper articles about its resolution.

[citation needed] BBC Books published some of Conan Doyle's original collections and novels as tie-in editions, with cover art featuring Cumberbatch and Freeman.

[187] The experience, which is built in the West 12 shopping centre in Shepherd's Bush and designed by the escape room creators of London's Time Run,[188] begins in 221B Baker Street and requires teams to solve mysteries to progress along through the 60-minute game.