Ireland, the dark ages. In the sacred city of Armagh, the High Druid Cathbad rules. To confront both the external and internal enemies of the Kingdom of Ulaid, he is helped by faithful helpers — Moyriot, a Woman-Druid, and the young successor Mangor.
Ingel One-eyed, the Bastard son of King Conaire, ruler of the Kingdom of Oriel, dreams of overthrowing his father and seizing power. To do this, he enters into a criminal alliance with his mother's uncles, co-rulers of the Kingdom of Fermanagh. The conspirators attack the Kingdom of Oriel and ravage the capital, the sacred Tara. Fleeing from the villains, Deichtine, the daughter of the High Druid of Cathbad and the concubine of King Conaire, hurriedly leaves Tara and returns to Armagh. Cathbad is vigilantly taking care of his daughter, but not only because of his fatherly feelings: according to the prophecy, it is Deichtine who will have to give birth to a child, who will later become King and unite disparate lands. Only then will the torn land of Ireland find peace, and the time will come for its prosperity.
The successor of Cathbad, Mangor, using the ancient magic of the Druids, invokes the spirit of the war goddess Morrigan and leads the valiant warriors into a fierce battle with the hated enemies.