Ancient Ireland. Dark Ages.
In the sacred city of Tara, ruled by King Conaire, preparations are underway for the Samhain celebration. On this day, Samhain opens a passage to the Otherworld. A conflict is brewing between King Conaire and his wife Fiona. This is due to the illegitimate son of King Ingel One-eyed. He behaves defiantly and does not respect the Queen and her daughters. Fiona intends to overthrow the king and kill Ingel. Cathbad and his youngest daughter Deichtine travel to Tara for the Samhain festival. After which Cathbad, the king and their retinues travel to the Sacred Valley to perform the proper ritual. During the ritual, Cathbad predicts difficult times for the sacred Tara.
Cade, laird of Tailtiu and subject of King Conaire, falls in love with Deichtine. The female druid Moyriot, who accompanied Cathbad, learns of a conspiracy against King Conaire.
On the night of Samhain, Cade enters the Otherworld. He spends the night in the arms of a princess from the Otherworld named Ethniu. But he refuses to stay with her. Then Ethniu curses Cade and his beloved Deichtine.
A mercenary tries to kill Ingel One-Eye. Ingel is between life and death. At this moment he finds himself in the realm of the god of war Toutatis. Toutatis promises to keep Ingel alive in exchange for his oath of allegiance. Laird of Tailtiu marry Deichtine. King Conaire intends to make Deichtine his concubine. Young Lady of Tailtiu tries to resist the wishes of the king.