"Prophet," the second novel in the acclaimed historical-fiction series "The Chronicles of Iona" (named to "Kirkus Reviews'" Best of 2012; Silver Prize Winner, "ForeWord Reviews" 2012 Book of the Year Awards, Historical Fiction), continues the story of the two men who laid the foundations of the Scottish nation, an Irish monk, Saint Columba, and a Scottish warlord, Aedan mac Gabran. They were a real-life sixth-century Merlin and King Arthur and their story has never been told. It is 567 A.D. Four years after journeying with the Scottish warrior Aedan mac Gabran into the land of the wild Picts,...