Earth Two. A new home for the survivors of the fleet, the men and women who battled against seemingly insurmountable odds to survive the assault of the First Imperium and to destroy the homicidal Regent, the artificial intelligence committed to their destruction.

They have prospered in the years since their arrival, adapting the technology of the First Imperium to build a new and prosperous republic. But as the fear of the First Imperium recedes, cracks have begun to appear, conflicts looming that threaten to destroy all they have worked to achieve.

There are rivalries between the clones known as Tanks and the NBs, naturally born humans - disputes driven by envy, resentment. And on the fringe of the new society, the enhanced genetic hybrids known as Mules are feared by both groups, though they continue to decipher First Imperium technology for the benefit of all.

But there is a far greater threat lurking in deep space, for the Regent was one of two, and its copy activated automatically upon its destruction. It has been planning, exploring, building vast fleets of new warships, and now it is ready to strike at a divided republic, to accomplish what the Regent failed to do. It is ruthlessly single-minded, existing for a single purpose. And that purpose is vengeance.