Set in Brin's Uplift universe in which no species can reach sentience without being "uplifted" by a patron race.  Humanity is unique in this galaxy since unlike other races, humanity has no patron, making it a source of considerable interest and controversy, especially since humanity is working to uplift neo chimpanzees and neo dolphins as their own clients.  As a “salvage world,” Garth was given to the despised Earthlings, assigned to reclaim it from the brink.  The planet was almost wrecked by its previous occupants, the Bururalli.  Many senior patron - leaders of the Five Galaxies - hope humanity would be unable to restore Garth, but it is now surging back, tended by human and neo-chimpanzee colonists.  As galactic armadas clash in a quest of the ancient fleet of the Progenitors found by the Earthship Streaker, a brutal alien race seizes Garth.  The various inhabitants must battle their overlords or face ultimate extinction.  At stake is the existence of Terran society and Earth, and the fate of the entire Five Galaxies.