The Burning Tree - Salvation: Book 1 of the Post-Apocalyptic Disaster series

An asteroid strike killed billions, leaving only a small number of survivors to rebuild civilization. The bunkers constructed in anticipation of apocalypse were designed for a different catastrophe than the one that occurred. In the underground bunker Salvation, conditions deteriorate for the residents of Level Three, who discover they have been preserved only to serve as a slave class. A single accident triggers a cascade of fear and rumor throughout the community, turning neighbors against one another as time becomes critical. For most inhabitants, this signals the end. Callie and her friends see one possible path to survival: escape to the surface. To reach it, they must endure a night of extreme terror. The question remains whether they can survive the horror ahead and establish a new life above ground, or if these final hours will be their last.