 For a while, the surface Cheela struggle to keep the rudiments of civilization, but eventually a barbarian conqueror arises.The Cheela in space and their human friends watch helplessly as a new dark age ensues.The second half of the story tells the heroic tale of how the space-bound Cheela, with a little help from the humans, eventually are able to land again on the surface, defeat the barbarian tyrant, and start to rebuild Cheela civilization.