The idea of ancient aliens visiting Earth is a well-worn one, but it's only the springboard for this tale, which is not about ancient aliens or Earth. Instead it's about the various human communities culled from Earth long ago and transplanted to another world. About how their cultures/societies developed along both different and similar paths.

On this new world, a group of Vikings evolve over the centuries into a cutthroat corporate culture of racial purists in an early industrial society, while retaining the vestiges of their traditions and mythology. The "corporatocracy" has designs on the lands populated by "horse men" (various tribes of Sioux who still cling to their old ways). Meanwhile, the upper caste Aesir must deal with the discontent and insurrection of their own worker caste, the Vanir.

A member of the Skaldoran warrior class is sent to infiltrate the savages, but becomes enamored with them. Separately, an Aesir doctor, disgusted by his countrymen's lack of regard for the horse men, becomes an inspirational figure among the native people who believe his coming has fulfilled a prophecy. When the chairman of the corporatocracy discovers there's a native herb which may be the cure for a disease that ravages the Aesir, as well as being the secret to longevity, war ensues. Eventually the two outsiders will join forces to lead the tribes against the Nordic invasion.

This epic tale of adventure and arrogance, discovery and desire, courage and greed, is ultimately a character story which follows several individuals. Red Sky, Blue Moon is a milieu novel with thematic echoes of Dune, Dances with Wolves, and The Last Samurai--meaning, at its heart, it's about strangers in strange lands.