Two hundred years ago, Adela de Montgarde, the brilliant astrophysicist, conceived the centuries-long plan to forestall the death of Earth's sun, thus preserving the original genetic material of the Empire of the Hundred Worlds-and of the Emperors who enabled her visionary plan.

Now Adela emerges from cold sleep to oversee the final stages of her great work. She awakens to an Empire transformed: her son Eric is Emporer, faster-than-light travel has finally been achieved, and humanity has spilled out to innumerable new planets, far beyond the Empire's Hundred Worlds.

In the twilight of the Empire, human and alien factions vie for advantage, while Adela's awesome feat of stellar engineering approaches its final fruition: the preservation and re-invigoration of the fearsome light at the heart of humanity's first solar system... the saving of Earth's Sun.