When Natani, a young girl from the Seven Rivers Tribe, is injured in a raid she is lucky to have survived. Left for dead, she is discovered by a patrol vessel and taken to Asu, a city of Atlantis where she isn't exactly made to feel welcome. Only one person, an aging, retired Frontier Guard named Vatriculos, shows the girl any kindness. After she heals from her injuries and learns some of the Atlantean language, Natani tells Vatriculos of her wish to locate her people. With half of Asu looking for them, they embark upon her quest. Where Natani of the Seven Rivers was out of her element walking the streets of Asu, her companion is out of his in the wilds of the Paleolithic where it is all the girl can do to keep him from getting himself killed. The pair learn much from one another as they carve a path from Atlantis to the Valley of the Seven Rivers, surviving terrific obstacles. But, unbeknownst to the mismatched pair, the Council of Asu, believing the girl possesses knowledge that will enable Atlantis to wipe out their enemies and ensure their conquest of a world, details a tracker to locate them and return the girl to Asu. Will the girl's companion turn his back on his country, or will he ensure the safety of Natani and her people, perhaps at the peril of his own?