After a dimensional fracture scatters humanity, sixteen-year-old Cassi Dyson wakes in Cimerrion, a world where people from Earth—people like her—are seen as a threat.

To survive, she becomes Callasandra and is forced into The Camp, a place where sixteen-year-olds are trained and every move is watched. When a quick-witted fellow student discovers her secret, he introduces her to the Antistasi, a resistance group working to bring down the oppressive regime.

Desperate to find her family, Cassi turns to the Antistasi, willing to risk everything, only to learn that one wrong move could make her—and anyone who dares to help her—vanish forever.