Twin sisters Kassia and Guinevere have been raised their entire lives within the comfortable confines of the Citadel, the home of a powerful religious sect. The latest of a vital bloodline, one of the two will someday be chosen to rise above their station and become a human vessel for their beloved, omnipotent god. However, there is much that has been withheld from them - knowledge of ancient history, unholy evils, and the arcane magic that their society has scorned for centuries.