Mike Mulvaney, a scientific prodigy who spent four years as a Maine after his father was almost killed in 9/11, went for a hike in the Adirondacks. He unknowingly walked through a star gate or portal to another world. The planet Cornu was settled by humans in the distance past who came through gates from earth. There were changes to human genes that strongly influenced human society. More women than man dictated multiple wives. Low fertility and birth rate with low population growth limited large scale conflicts. Pheromones played an important part in picking mates and in libido.
The technology was early eighteenth century and progress was slow. Much of the progress came from the very rare person who came through the gates. While wars weren't waged due to population loss, bloody dynastic plots were hatched and waged. One particularly nasty and deadly one was conceived against the royal family of Nordia by a rival kingdom. When he arrived, Mike was disoriented and worried about his sanity. Was this real or a delusion? He gathered himself and slowly set out to explore this new world and soon found himself hip deep in the plot.
Contains mature themes.