 Sherlock is a British @-@ American 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 . Ten episodes have been produced , with three @-@ part series airing in 2010 , 2012 and 2014 , and a special episode airing on 1 January 2016 . A fourth series has been commissioned , which began filming in April 2016 for an intended 2017 release . The series is set in the present day , while the one @-@ off special partly features a Victorian period fantasy resembling the original Holmes stories . Sherlock is a co @-@ production between the BBC and WGBH Boston for its Masterpiece anthology series on PBS , with Sue Vertue and Elaine Cameron of Hartswood Films serving as 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 . 
