 The show was produced by Hartswood Films for BBC Wales, while BBC Worldwide also provided co-production funding. Production was also co-produced by PBS, a network of public-service broadcasters in the United States, for WGBH-TV's Masterpiece Mystery! strand. Filming of the pilot episode, written by Moffat and directed by Coky Giedroyc, commenced in January 2009. The following January (2010), the first set of three episodes entered production. Paul McGuigan directed the first and third episodes and Euros Lyn directed the second. The three episodes were filmed in reverse order of their broadcast.
