Following the events of Pulse Point, 12-year old Ama and the other Underlanders living in a world of darkness dig for brine, the City’s real energy source. Underland is a dangerous place: cave-ins, starvation and illness areconstant threats. When their leader deserts them, Ama goes looking for him and stumbles on two Citizens. Neither knew the other existed.18-year old Sari lives in the City, blissfully unaware of what goes on beneath her feet. The disappearance of her best friend, Kaia, has left her feeling isolated. A chance encounter with her sister leads her to join a group called the...