The Happiness Patrol

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

The TARDIS arrives on the planet Terra Alpha where the Doctor and Ace discover a society in which sadness is against the law - a law enforced with considerable zeal by the brightly uniformed Happiness Patrol. The planet is ruled over by Helen A with the aid of her companion Joseph C and her carnivorous pet Stigorax named Fifi.

The penalty for those found guilty of unhappiness is death in a stream of molten candy prepared by Helen A's executioner, the robotic Kandyman, and his associate Gilbert M. The time travellers help to foment rebellion amongst the downtrodden population and the subterranean Pipe People - the planet's original inhabitants - and Helen A is overthrown.

Joseph C and Gilbert M escape in a shuttle, while the Kandyman is destroyed and Fifi killed. Helen A finally realises that happiness is nothing without the contrast of sadness.

3 out of 110 (2.7%) raters say this story requires a previous story.