Isabellae is about to fight alongside her Celtic parents. In front of them, it is not the Normans who appear, but monsters by hundreds, straight out of the earth: the gods Formoires, the first inhabitants of the island of Emerald, who sowed terror there for centuries before being sent back from where they came from. The Celtes will have to choose: slave of the Normans, vassals of the gods or... free men.