Mild-mannered and hapless council worker Stewart gets enlisted into helping three members of the Gu’un alien race – who have taken over Earth – set up their rule of the United Kingdom in the buildings of the Clitheroe Borough Council, while being tempted by the Anti-Alien Alliance (AAA) determined to overthrow them. Stewart tries to cope between the widely different approaches to ruling along the three Gu’uns, by attempting – with fluctuating success – to ingratiate them to the British people, and avoid at all costs the ultimate fate of getting flushed into space.
