This English crime drama series, based on books by Caroline Graham, is filmed mostly in the villages and towns of the rural county of Buckinghamshire, which lies to the east of Oxford and the north west of London, though sometimes straying into other neighbouring counties. John Nettles plays Chief Inspector Tom Barnaby of the Causton C.I.D., a laconic, down-to-earth detective who faces many ingenious and remarkable murders (usually several in each episode) amid the eccentric denizens of Middle England. For the first twenty-nine episodes, until November 2003, Barnaby's partner in detection was Sergeant Gavin Troy, played by Daniel Casey. From the beginning of 2004, Troy was replaced by Sergeant Dan Scott (John Hopkins). Other regulars include Tom's wife Joyce and his daughter Cully, who sometimes get mixed up in the plot. Midsomer Murders has now been sold to more than a hundred countries around the world.