Clementine has spent her whole life preparing for her 16th birthday when she'll be tested for Extraction, in the hopes of being sent from Kiel's toxic Surface to the much safer Core, where people live without fear or starvation. When she proves promising enough to be "extracted," she must leave without Logan, the boy she loves. Torn apart from her only sense of family, Clem promises to come back and save him from brutal Surface life. What she finds initially at the Core is a utopia compared to the Surface-it's free of hard labour, gun-wielding officials, and the moon's lethal acid-but life is anything but safe, and Clementine learns that the planet's leaders are planning to exterminate Surface dwellers-and that means Logan, too. Trapped by the steel walls of the underground and the lies that keep her safe, Clementine must find a way to escape and rescue Logan and the rest of the planet. But the planet's leaders don't want her running - they want her subdued.