In the third entry chronicling the rise of Christian kings in Britain, Oswald dies and the great pagan king Penda becomes overlord in his place. To stand against the increasingly powerful Penda, Oswiu, king of Bernicia, tries to unite the smaller neighboring kingdoms by marrying a daughter of Deira. But the struggle for power leads Oswiu to order the assassination of the king of Deira. He wins the throne but loses the approval of the people. In atonement, he establishes a monastery at the site of the slaying.
What will happen when Oswiu and High King Penda at last meet in battle? Though the kingdom may become politically one, both the Celtic and Roman strands of Christian faith vie for supremacy, mirroring the king's own struggle for power.