The Last Dome (Allendian Post-Apocalypse, #3)

Sidney has lived in the Red for a few years. She's cured of the flu and has new friends, possibly even a new family.
But she soon learns that Allendians and their history are more complicated than she or Nayne had imagined. Before long, she learns the biggest lesson of her young life: that nothing in Allenda—and not a single Allendian—can truly be trusted.
As her entire world verges on destruction, a sand storm is raging on the horizon: a tempest the likes of which no Allendian has ever survi...