Lt Commander Grimes arrives on the forgotten planet Sparta where humans had long ago settled and have since modelled their society on the ancient Greek city-state of Sparta. Indeed, Sparta, originally an early Federation colony, has been out of touch for so long the people have forgotten they’re a colony. Over time a civilisation based on war and violence and crude pleasures has developed. It is also a planet where human beings (all men) are produced by birth machines and women are unknown.
The story is told from the perspective of Brasidus, one of the small planet's policemen. Never having laid eyes on a woman, or imagined that such strange beings exist, he and most other residents of the planet Sparta think that the female crew of Grime's ship, including Margaret Lazenby (Grime's sometimes sex partner) are deformed men, and they can’t fathom what the peculiar bumps on their chests are.
Although Grimes and his crew have the best intentions during their stay on the planet they eventually manage to turn the whole society on its head. Horrific events unfurl and truths become known, setting in motion changes that have a profound effect on the Spartan society.