Saint Leibowitz and the Wild Horse Woman

Millennia have passed since the Flame Deluge, yet society remains fragmented, pockets of civilization besieged by barbarians. The Church is in turmoil, the exiled papacy struggling to survive in its Rocky Mountain refuge. To the south, tyranny is on the march. Imperial Texark troops, bent on conquest, are headed north into the lands of the Nomads, spreading terror in their wake.
Meanwhile, isolated in Leibowitz Abbey, Brother Blacktooth St. George suffers a crisis of faith. Torn between his vows and his Nomad upbringing, between the Holy Virgin and visions of the Wild Horse Woman of his people, he stands at the brink of disgrace and expulsion from his order. But he is offered an escape - of sorts; a new assignment as a translator for Cardinal Brownpony, which will take him to the contentious election of a new pope and then on a pilgrimage to the city of New Rome. Journeying across a continent divided by nature, politics, and war, Blacktooth is drawn into Brownspony's intrigues and conspiracies. He bears witness to rebellion, assassination, and human sacrifice. And he is introduced to the sins that monastery life has long held at bay.
This introduction comes in the form of Aedrea, a beautiful but forbidden "genny" living among the deformed and mutant castouts in Texark's most hostile terrain. As Blacktooth encounters her again and again on his travels - in the flesh, in rumors of miraculous deeds, and in the delirium of fever - he begins to wonder if Aedrea is a she-devil, the Holy Mother, or the Wild Horse Woman herself.