Four to Doomsday is the second serial of the 19th season of the British science fiction television series Doctor Who, which was first broadcast in four twice-weekly parts on BBC1 from 18 to 26 January 1982. The serial is set almost entirely on the spaceship of the alien Urbankan Monarch (Stratford Johns). In the serial, Monarch plots to invade Earth for its minerals using a deadly toxin to wipe out humanity so he can continue to make improvements to his ship. Plot The TARDIS materialises on board a vast and advanced spacecraft, observed by a hovering surveillance device which conveys the arrival of the crew to an observing being in control of the vessel. The TARDIS crew become separated and the Fifth Doctor and Tegan reach the bridge where the green-skinned commander introduces himself as Monarch, ruler of Urbanka, and his associates and fellow Urbankans are the Ministers of Enlightenment and Persuasion. The leader is intrigued by talk of current Earth civilisation and reveals their ship is bound for Earth. Shortly afterwards Enlightenment and Persuasion assume human forms, dressed in garments Tegan designed to demonstrate contemporary Earth fashions. The TARDIS crew are reunited as guests, and it becomes apparent that there are four distinct human cultures represented on the vessel by a small group of humans – Ancient Greeks, the leader of whom is the philosopher Bigon; Chinese Mandarins and their leader Lin Futu; Princess Villagra and representatives of the Maya peoples; and Kurkutji and his tribesmen, of a very ancient Australian Aboriginal culture. The Urbankans have made periodic visits to Earth, each time getting speedier in their journeys. This time they have left their homeworld after erratic solar activity, storing three billion of their species on slides aboard their craft. It seems that the current journey is their last and that they now wish to settle on Earth, which they are due to reach in four days. The Doctor becomes suspicious of Monarch and soon learns he does not plan on peaceful co-existence. Instead, he has developed a poison that reduces the intended in size to conquer Earth, which will be unleashed before the Urbankans disembark. He also learns that the humans aboard are not descendants of the original abductees, but are the original people taken from Earth and converted into androids, like the three Urbankans walking around on board. Monarch describes the era prior to his conversion of