The extermination of Earth is at hand. With his increasingly irrational leadership, Basil Wenceslas, chairman of the Hansa, has driven humanity into a corner. His punitive treatment of the Hansa colonies and the Roamers, as well as his refusal to aid an embattled Theroc, have made enemies for the people of Earth. Enemies that the Hansa cannot afford - not when Wenceslas is struggling against revolt by soldier compies, who decimate the military by stealing ships and slaughtering soldiers; and betrayal by the Ildirans, led by Jora'h the Mage-Imperator, who is secretly scheming with the hydrogues to annihilate Earth.

Now disparate factions of humanity must plan for their own salvation. Worldtrees allied with humans on Theroc have rallied hulking, thorny tree battleships. Roamers work with powerful water entities, the wentals, to seed planets everywhere with a growing force to challenge the hydrogues.

But when the final battle with the hydrogues is joined, who will aid the people of Earth?