premise: The Tenth Doctor appears in at least one episode of Doctor Who.
hypothesis: The tenth series of the British science fiction television programme Doctor Who premiered on 15 April 2017 and is set to consist of twelve episodes , after it was released in July 2015 that BBC Worldwide had invested in a tenth series of the programme in its annual review . Preceded by a Christmas special in December 2016 , `` The Return of Doctor Mysterio '' , the series is the third and final series starring Peter Capaldi as the Twelfth Doctor , an incarnation of the Doctor , an alien Time Lord who travels through time and space in his TARDIS , which appears to be a British police box on the outside ; Capaldi announced in January 2017 that he would be stepping down from the role after the tenth series . Doctor Who (series 9) . This is the second series starring Peter Capaldi as the Twelfth Doctor , an alien Time Lord who travels through time and space in his TARDIS , which is disguised as a British police box . The Tenth Doctor is an incarnation of the Doctor , the protagonist of the BBC science fiction television programme Doctor Who , who is played by David Tennant in three series as well as nine specials . As with previous incarnations of the Doctor , the character has also appeared in other Doctor Who spin-offs .