The Doctor and Romana visit the Leisure Hive on the planet Argolis, the surface of which is uninhabitable following a twenty minute nuclear war between the Argolins and their enemies, the Foamsi. The Argolins themselves are now sterile. Pangol, the youngest, was created by the Tachyon Recreation Generator, a machine that runs games in the Hive. He now secretly plans to use the Generator, modified by an Earth scientist named Hardin, to recreate himself many times over, forming an army of duplicates to destroy the Foamsi. Pangol's mother Mena, the controller of the Hive, is meanwhile coming under pressure from a supposedly human finanacier, Brock, to sell it to the Foamasi ...