Shaken by the violence of climate change, the extinction of thousands of species, and the exhaustion of resources, the Earth lets out a cry of alarm.
Faced with the planet's distress, humans make a final bid for survival and set up new social orders. America succumbs to bloody purges, while Europe announces the Systra Law.
This is the world Callie is born into. A smart girl, loved by her parents, her life changes when a little sister, Kaya, is born. The Systra Law comes into play, the children are separated, raised far from their own, in different environments, for the day when they shall meet... and fight. For there can only be one. The other must die.