From the introduction: Near the end of the 87th migration, the Ancients of the Deep convened a gathering: for one of theirs, the Progenitor , had shared his divine knowledge with mortals beyond the veil. The balance between Light and Dark was under threat, and the Progenitor was cast out for its transgressions. Now, a new god must rise to take the Progenitor’s place, chosen by the Ancients from among the worthy, brought together from the Light and Dark places of the world. Though the Progenitor’s mortal followers were damned to the last, a number of its offspring existed - and these unique individuals all carried a fragment of its divine power. They are known as Demigods.