In 1215, the court of King John (Gerald Flood) has come to the castle of Sir Ranulf Fitzwilliam (Frank Windsor) to demand more taxes. The Lord refuses and the King insults him. To defend his honour, the Lord’s son Hugh (Christopher Villiers) must battle the King’s champion, Sir Giles Estram (Anthony Ainley, the Master) in a joust. Sir Giles wins easily, but the joust is disturbed by the materialization of the TARDIS. The Doctor, Tegan, and Turlough are seen as demons, but the King welcomes them.
As soon as he realizes the date, the Doctor knows the King is a fake. The real King is in London, taking the Crusaders’ oath. Sir Geoffrey de Lacy (Michael J. Jackson), Sir Ranulf’s cousin, arrives at the castle and confirms that fact. Sir Gilles is all set to torture him as a liar, when the Doctor intervenes, unmasking Sir Giles as the Master. The Master flees in his TARDIS, as he does, which is disguised as an Iron Maiden.
The King knights the Doctor and gives him the run of the castle. After Sir Geoffrey is killed by the Master, the Doctor discovers that the King is really a robot. He is a war-weapon from the planet Xeriphas that the Master has stolen. Its name is Kamelion, as it can take on anyone’s shape. The Master hopes the phoney King John will behave so badly it will provoke a rebellion against the real King, thus preventing the signing of the Magna Carta, stifling parliamentary democracy.
The Doctor engages in a battle of wills over control of Kamelian. The Doctor steals the robot and takes it clean away in the TARDIS, foiling the Master’s plan. Kamelian (voice of Gerald Flood) reverts to its natural gleaming form and thanks the Doctor for his release. This is one of the rare two-episode stories. Part One was advertised as the six hundredth episode of Doctor Who. Kamelion was created by computer expert Chris Padmore and software designer Mike Power, impressing producer John Nathan-Turner, who had a story written by scriptwriter Terence Dudley to showcase the creation. Unfortunately, Mike Power died in a boating accident and Kamelion only appeared twice. Sir Giles Estram (anagram of Master) was listed as being played by James Stoker (anagram of Master’s Joke) to keep secret the Master’s participation.
The Iron Maiden, an anachronistic detail, that played the Master’s TARDIS turned up in an episode of Black Adder. Peter Davison and Anthony Ainley got to show off their fencing skills, but the story received poor reviews. The costumes and sets are as impressive as you would expect from the BBC, but the story amounts to very little. Even the Doctor wonders what the Master is doing there. The Magna Carta had no historical impact in the 12th Century; it wasn’t until the 17th that it got its reputation as the beginning of democracy. The whole story seems to have little purpose other than to showcase Kamelion—a real robot on Doctor Who—but the only guy who could make it work, apparently, up and died.