This volume starts where volume III left off. They go on to meet the Galactic Empire finding them far different than human intelligences. When the asteroid impacted Earth twenty years ago, the colony ships had already left for new planets and no life was expected to survive, but a few people did survive. Part of this book is the story of those survivors. The novel then skips ahead to when the SHIP finds their little Earth civilization again and contacts those survivors. The changes to Earth are documented. Leaving Earth again they discover traces of the Martians/Atlanteans that left Earth over 10,000 years ago.