The Intra-Earth Chronicles

In the year 2444, two noble sisters, Sasha (15) and Adrianne (11), have survived a nuclear fallout, only to be torn apart. The ground splits open, and Adrianne is thrown from her horse, plummeting into the ravine. Spurned on by the hope that Adrianne lives, Sasha embarks on a journey through the desert to face the ravine that claimed her only sister. Meanwhile, deep within the earth, Adrianne is running for her life. She took something that did not belong to her.

Noble sisters Sasha and Adrianne, along with their faithful companions—a satellite and a tiger—have defeated Tartarus, freeing the subterranean city of Mu from a dangerous tyrant. In gratitude, the council gifts them a powerful nuclear machine. Their mission is to journey to the surface with the machine and jump-start civilization. However, Tartarus, hiding like a snake in the grass, soon gains possession of the nuclear machine.