The story centers around Oisin, the son of the goddess Niamh and the mortal poet Fionn. As Oisin grows up, he becomes increasingly fascinated with the stories of the Tuatha Dé Danann, the ancient gods and goddesses of Ireland. Despite his mother's warning, Oisin sets out to find the Tuatha Dé Danann and discover the truth about his heritage. Along the way, he meets a fairy queen who tells him that his mother is actually a powerful goddess and that his destiny is to join her in the land of the immortals. Oisin must make a difficult decision between staying with his mortal family or embracing his immortal destiny. The story explores themes of love, sacrifice, and destiny, as Oisin struggles to come to terms with his true identity and place in the world.