Seventh-century Ireland is becoming a land of saints, scholars, and spiritual foster mothers as well as warriors. The boy Aidan, a descendant of Saint Brigid, is formed by all of these as well as by a pilgrimage, aborted by an Arab uprising, on which he meets a follower of the Prophet Muhammad. He is transferred to Iona, the mother-house of Saint Columba's family of monasteries, where his character is forged. Aidan becomes guest-master to challenging visitors, one of whom conducts a mysterious affair, suffers a midlife crisis, and develops friendships with royal Saxon exiles at the Dunadd...