Question: Natasha O'Keeffe is known for her role of Emelia Ricoletti in "Sherlock", the crime drama tv series based on which author's detective stories?
Context: Martin John Christopher Freeman (born 8 September 1971) is an English actor, who became known for portraying Tim Canterbury in the original UK version of sitcom mockumentary "The Office", Dr. John Watson in the British crime drama "Sherlock", Bilbo Baggins in Peter Jackson's "The Hobbit" film trilogy, and Lester Nygaard in the dark comedy-crime drama TV series "Fargo". Umutsuz Ev Kadınları, is a Turkish comedy drama TV series, based on the American comedy drama TV series Desperate Housewives. Sherlock is a crime drama television series based on Sir Arthur Conan Doyle's Sherlock Holmes detective stories.  Created by Steven Moffat and Mark Gatiss, it stars Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as Doctor John Watson.  Thirteen episodes have been produced, with three-part series airing from 2010–2017, and a special episode that aired on 1 January 2016.  The series is set in the present day, while the one-off special features a Victorian period fantasy resembling the original Holmes stories.  "Sherlock" is a co-production of the British network BBC and the American station WGBH Boston for its "Masterpiece" anthology series on PBS, along with Hartswood Films, with Moffat, Gatiss, Sue Vertue and Rebecca Eaton serving as executive producers.  The series is primarily filmed in Cardiff, Wales, with North Gower Street in London used for exterior shots of Holmes and Watson's 221B Baker Street residence. Natasha Dervill O'Keeffe (born 1 December 1986 in Brighton) is an English stage, television and movie actress.  She is known for her roles as Abbey in the British television series "Misfits", Fedora in ITV's television series "Jekyll and Hyde", and as Emelia Ricoletti in the "Sherlock" New Year special episode "The Abominable Bride". The Last Pin is a series of mystery stories by author Howard Wandrei.  It was released in 1996 by F & B Mystery in an edition of 1,600 copies of which 100 were specially bound and released in a slipcase with Wandrei's "Saith the Lord".  The stories originally appeared in the magazines "Detective Fiction Weekly", "Private Detective Stories", "Detective Action Stories", "Spicy Detective Stories", "Romantic Detective" and "Black Mask" under Wandrei's pseudonyms Robert A. Garron and H. W. Guernsey. Get Christie Love!  is a 1974 made-for-television film and subsequent crime drama TV series starring Teresa Graves as an undercover female police detective who is determined to overthrow a drug ring.  This film is based on Dorothy Uhnak's crime-thriller novel "The Ledger".  However, the main character "Christie Opara"—a white, New York Police detective—was dropped completely and "Christie Love" emerged. Amazing Detective Di Renjie, also known as Shen Tan Di Renjie and Wu Chao Mi An, is a Chinese television series based on "gong'an" detective stories related to Di Renjie, a Tang dynasty magistrate and statesman.  Written and directed by Qian Yanqiu, the series starred Liang Guanhua as the titular protagonist, and was first broadcast on CCTV-8 on 6 August 2004.  The series was followed by three sequels: "Amazing Detective Di Renjie 2" (2006), "Amazing Detective Di Renjie 3" (2008), and "Mad Detective Di Renjie" (2010). "Sherlock" is a television crime drama that presents a contemporary adaptation of Sir Arthur Conan Doyle's Sherlock Holmes detective stories.  Created by Steven Moffat and Mark Gatiss, it stars Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as Doctor John Watson.  The first series of three episodes aired in 2010, while series two aired in 2012, and a third series aired in the first quarter of 2014.  The third series has become the UK's most watched drama series since 2001.  A single episode aired in 2016, as a Victorian-era special.  "Sherlock" has been sold to over 200 territories. Amazing Detective Di Renjie 2, also known as Shen Tan Di Renjie 2, is the second installment in a four-season Chinese television series based on "gong'an" detective stories related to Di Renjie, a Tang dynasty magistrate and statesman.  Written and directed by Qian Yanqiu, the series starred Liang Guanhua as the titular protagonist, and was first broadcast on CCTV-8 on 20 November 2006, two years after the first season.  It was followed by "Amazing Detective Di Renjie 3" in 2008, and "Mad Detective Di Renjie" in 2010. Sherlock Holmes (Russian: Шерлок Холмс , Sherlok Kholms ) is a Russian television crime drama series based on the Sherlock Holmes detective stories by Arthur Conan Doyle, and was aired in November 2013.  Some of the stories have never been adapted before.  It stars Igor Petrenko as Sherlock Holmes and Andrei Panin as Doctor John Watson.  Eight episodes have been produced, while the first episode was aired in late 2013.
Answer: Sir Arthur Conan Doyle