The Underworld Plan

When the entire world is forced to move underground, resources run out. When resources run out, expedition teams have to be sent back above ground to get more. When expeditions teams have to go above ground, crazy, dangerous, and exciting adventures take place. And when crazy, dangerous, and exciting adventures take place, Cassandra Collins and her team have to make sure they get back to the Underworld with the resources they need, or their death is guaranteed.