As the series begins, the arrogant Hansa Chairman Basil Wenceslas begins grooming a replacement for the aging King Frederick. Basil looks to expand the human empire further through the discovery of alien technology from the extinct Klikiss race that will allow scientists to create a new star from a gas giant, turning cold moons into planets ripe for colonization. The most prominent human world aside from Earth is Theroc, a planet covered in semi-sentient worldtrees that is quietly independent from the Hansa. Theroc's "green priests" are able to commune with the trees and communicate telepathically across space when touching a treeling, making them indispensable for instantaneous communication across the galaxy. The Roamers are clans of industrious humans living a clandestine existence in the fringes of space, managing a profitable economy centered on the sale of the valuable stardrive fuel ekti and other commodities. The ignition of the gas giant Oncier reveals the existence of the elemental hydrogues, and the inadvertent hydrogue genocide at the hands of the humans incites the ire of the other hidden hydrogue populations across the galaxy. Their brutal retaliation and forced cessation of "ekti" collection threaten to cripple both the human and Ildiran civilizations, and serve as an effective declaration of war. The aggression of the hydrogues reawakens the verdani, the worldtree entities who had fled to Theroc after losing an ancient war with the hydrogues. Meanwhile, the Ildiran Mage-Imperator Cyroc'h struggles to hide his race's secrets and keep the centuries-old plan for ultimate Ildiran survival on track. And the amnesiac black Klikiss robots, left behind after their parent race's mysterious destruction, have secrets of their own.