The King ' s Demons ( TV story ) The King ' s Demons was the sixth and final story of Season 20 of " Doctor Who " . It introduced Kamelion , the first non - humanoid companion since K9 . Furthermore , it centred on a genuine historical figure " and " a significant event — King John and the signing of the Magna Carta — a formula which had been all - but - unseen since William Hartnell left the show . It also gave Peter Davison a chance to display his fencing skills . The Fifth Doctor became the third consecutive incarnation of the Doctor to have some skill with a blade , his immediate predecessors having swashbuckled in " The Sea Devils " , " The Masque of Mandragora " , and " The Androids of Tara " . Indeed , " Demons " provided a kind of rematch for the Doctor and the Master , echoing the earlier duel between the Third Doctor and . It was the last televised story to feature the Doctor - as - swordsman until David Tennant ' s debut in 2005 . Narratively , it ends with an unusual , " one - way , retrospective cliffhanger " . That is , it ' s only visible if " The Five Doctors " is seen immediately after " Demons " . At the conclusion of " Demons " , the Doctor promises to take his companion s to the Eye of Orion . Since the Doctor often makes promises of future adventures at the ends of stories , this doesn ' t appear to be a cliffhanger at all . It ' s only by seeing " The Five Doctors " that the audience realises he ' s kept a promise made in the previous story . Perhaps more crucial is the notion that the Master we see in " The Five Doctors " has been recalled to Gallifrey immediately after his 13th century defeat by the Fifth Doctor , a fact that , once known , can subtly change the viewer ' s perception of certain scenes in " The Five Doctors " . For years , this connection was fairly obvious on home video , because home video viewers were forced to buy a version of " The Five Doctors " on VHS , where the two stories had been bundled together . Following 2010 ' s separate release of this story on DVD , the cliffhanger will likely escape more viewers ' attention . Thanks to the dismal ratings for the first episode , this serial as a whole was the lowest - rated serial of the Fifth Doctor ' s run . It therefore contrasts with another two - parter , " Black Orchid " , which was the " highest " rated Davison story . ( REF : " The Fifth Doctor Handbook " ) Synopsis . The Doctor and his companions arrive at a medieval joust and are surprised to be greeted warmly by King John , who calls them his demons . But when a young nobleman returns , having just left King John in London , the Doctor realises that this king must be an impostor ! Then the Master makes an appearance and the Doctor ' s worst fears are confirmed . . . Plot . Part one . In March 1215 , King John of England is at the castle of Sir Ranulf Fitzwilliam to extort more taxes . When the lord refuses to pay , the King insults him . To defend his honour , his son Hugh takes on the King ' s champion , Sir Gilles Estram , in a joust . The latter wins easily , though the joust is disturbed by the arrival of the TARDIS . The Doctor , Tegan , and Turlough are greeted as demons and welcomed by the King . Having established the date , the Doctor concludes the King is not himself - in fact , he is not the King at all . History records that John is actually in London , taking the Crusader ' s Oath . Sir Geoffrey de Lacy , the cousin of Sir Ranulf , arrives at the castle and confirms the Doctor ' s belief . Sir Gilles is about to torture him as a liar during a royal banquet when the Doctor intervenes . It seems the King ' s champion is not who he claims to be , either : Sir Gilles sheds his disguise and reveals himself to be the Doctor ' s arch - nemesis , the Master , who aims his tissue compression eliminator at the Doctor . . . Part two . The Master flees in his own TARDIS , which had been disguised as an iron maiden ( torture device ) . The King knights the Doctor as his new champion , and he is given run of the castle . After a series of mishaps , including the death of Sir Geoffrey at the Master ' s hands , the Doctor confronts the King and the Master and discovers the truth . The monarch is really Kamelion , a war weapon found by the Master on Xeriphas , which can be mentally controlled and used to adopt disguises and personas . With Kamelion disguised as King John , the Master intends that he will behave so appallingly as to provoke a rebellion and topple the real king from his throne , thus robbing the world of Magna Carta , the foundation of parliamentary democracy . It is a small plan on the Master ' s usual scale , but nevertheless particularly damaging to the normal progress of Earth society . The Doctor resolves the situation by testing the Master in a battle of wills for control over Kamelion . He takes control of the robot and steals it away in the TARDIS , thus foiling the Master ' s scheme . Kamelion reverts to its robot form and thanks the Doctor for his assistance and rescue . To Turlough ' s surprise and Tegan ' s dismay , the Doctor accepts Kamelion as a new travelling companion aboard the TARDIS . Tegan insists that she does not wish to be returned home , however , and the Doctor admits that the co - ordinates are already set for the Eye of Orion . Home video and audio releases . DVD releases . This story was released on Region 2 DVD on 14 June 2010 as part of the Kamelion Tales boxset , and as an individual release in Region 1 on 7 September 2010 . The disc set includes a restored version of the story , as well as the following special features :