Over a millennium ago earth was practically destroyed and not many people were left who did not go in to space on the great arks.
To make sure no one followed and in the hope that Earth would repair itself the last group of astronauts launched bombs above earth which fried all electric devices and put civilization back to the dark ages.
People have reformed society in many different ways.
It is about these people this story is told.
Book 1: Harbour City: 1134
Book 2: Harbour City: 1138