In the town of Segontium a wild storm washes a fugitive ashore. He brutally rapes the granddaughter of the ruler of the Deceangli tribe, leaving her to bear his son, Myrddion Merlinus (Merlin). Spurned as a demon seed, the child is raised by his grandmother and, as soon as he turns nine, he is apprenticed to a skilled alchemist who hones the boy's remarkable gift of prophecy.

Meanwhile, the High King of the Britons, Vortigern, is rebuilding the ancient fortress at Dinas Emrys. According to a prophecy, he must use the blood of a demon seed--a human sacrifice--to make his towers stand firm. Myrddion's life is now in jeopardy, but the gifted boy understands that he has a richer destiny to fulfill. Soon Vortigern shall be known as the harbinger of chaos, and Myrddion must use his gifts for good in a land besieged by evil. So begins the young healer's journey to greatness . . .