Once before, the sentient races in the known part of the galaxy - humans, Orions, Ophiuchi and Gorm - had united to defeat alien invaders. The "bugs," who regarded all other intelligent beings as food, had been defeated at a terrible cost. Decades later, the gallant warriors of that victory have grown old, while new generations have grown dangerously complacent. Long ago, a doomed planet's population built a huge fleet of ships, each ship larger than a city, and fled their world before its sun went nova. Centuries later, the fleet has arrived at the world they intend to make their new home. They regard the fact that the planet is already colonized by humans as a mere inconvenience, the more so since their mode of communication is so different from anything humans use that they do not consider humans and their allies to be truly intelligent. This time, the intelligent races of the old alliance will not have to worry about becoming an invader's meal - but that will be small comfort if the invaders decide that genocide is justified for their own survival...