Fleet of Worlds

Fleet of Worlds is a science fiction novel by Larry Niven and Edward M. Lerner, published in 2007 and set in the Known Space sequence shortly after the events of the short story At the Core. It concerns the liberation of New Terra from the Concordance of the Pierson's Puppeteers, and it introduces a new intelligent species to that setting, the Gw'oth.

Kirsten belongs to a human population that has served the Citizens for generations and is grateful for it, since the Citizens rescued her ancestors from a dying starship and gave them a home world. What the Citizens do not know, or are not told, is where those humans actually came from, and that gap in their account of themselves is the hinge of the story.

When a chain reaction of supernovae at the galactic core releases a wave of radiation that will sterilise the galaxy, the Citizens take their worlds and run, and somebody has to scout ahead. Kirsten and her crew volunteer, working under the eye of their Citizen mentor Nessus, and the dangers they look for in the fleet's path turn out to include long-hidden facts about their own history.