Most humans on Earth live in a small number of elaborate, high-tech castles as idle aristocrats primarily concerned with aesthetics, pastimes and questions of honor and etiquette. Only a small minority of humans live free lives outside of the castles, and are considered barbaric by the inhabitants of the castles. Various alien races serve the latter.
One day, one of those slave races, the Meks, revolt and start besieging the castles. One by one, the castles fall and their residents are killed, until only Castle Hagedorn is left. Most of the decadent castle denizens choose to ignore the danger. One of them, Xanten, decides to fight the Meks and searches for allies inside as well as outside the castle.
After a short and hard battle, Xanten and his allies win. Concluding that humanity cannot go on depending on slave labor, they send the surviving Meks back to their native planet, Etamin 9.