Kadmeron, a young hunter-gatherer from Western Europe, prepares for his shamanic initiation. The horse's spirit comes to warn him during his sleep of an imminent catastrophe. The incessant rains that have falling on the Saveronacs people for months have weakened the soil. They have also profoundly changed the behavior of humans and animals. While participating in a deer hunt, Kadmeron finds himself confronted with the destruction of the camp where his tribe has lived for generations. Indeed, Mother Earth has unleashed the waters' fury which destroys everything in its path. Why such an inexplicable anger? Left to himself, Kadmeron must act despite heartbreak and despair.

In her village in the Gorge of the Ancestors, far east near the New Sea, Zia follows the learning of any young girl of her own kind. Life unfolds at the rhythm of the seasons, with an apparent calm. Her mother the Matriarch intended her to become a priestess and to ensure, like her, the perpetuation of traditions. But this is not what Zia dreams of for her future. She would prefer to devote herself to raising animals and studying plants. Her grandmother understands her and encourages her to find her way. However, in accordance with maternal will, Zia is finally forced to embark on a dangerous quest at the source of the Great Mother River.

Kadmeron and Zia don't know each other yet, but each faces a turbulent fate. Will they be able to overcome the immense obstacles which stand in their way and which threatened pre-Neolithic humanity with extinction? Will their paths cross one day?