Ireland, dark ages. Ingel One-Eye, the bastard son of King Conaire, ruler of the kingdom of Ergial, 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 Fera-Mork. They attack Ergial and sack the capital, sacred Tara. Deirdre, concubine of King Conaire and daughter of the Archdruid of Cathbad, hastily leaves Tara, fearing her enemies, and returns to her father. And Cathbad's assistant Mangor decides to use the ancient magic of the Druids and summon the spirit of the goddess of war Morrigan...