Four To Doomsday

From: http://www.bbc.co.uk/doctorwho/classic/episodeguide

The TARDIS arrives on board a huge spaceship where the Doctor and his companions encounter the frog-like Urbankans and a population of human androids. The androids are drawn from four different ethnic groups - Greek (led by Bigon), Chinese (led by Lin Futu), Mayan (led by Villagra) and Aboriginal Australian (led by Kurkutji) - and perform regular displays of dance and other rituals termed 'recreationals'.

The Urbankans' leader, Monarch, aided by his ministers Persuasion and Enlightenment, is engaged in a complex scheme to plunder from Earth the raw materials needed to enable him to travel back in time and thereby confirm his belief in his own status as the universe's divine creator.

Monarch has a poison that he intends to use to conquer humanity so that Earth can be repopulated with his androids. The Doctor, however, throws a canister of the poison at Monarch, causing him to shrink away to virtually nothing.

5 out of 86 (5.8%) raters say this story requires a previous story.