Stranded on the far side of the moon with her friends, Scout Shannon waits for rescue from galactic central. Hunted by two sets of enemies, surrounded by an impenetrable barrier maintained by an almost alien class of humans, time runs short.Caught between two factions of a powerful trade dynasty, Scout fights to remain free and to protect her friends. But the people trying to make her their pawn barely seem human to her eyes. Fight them? She can barely understand them.With friends on both sides of the planetary blockade, Scout just needs to find a way to get her friends stuck on the inside to those waiting for them on the outside. But foes also lurk on both sides. And they hide among her friends. How to tell friend from foe? Scout better learn before the enemies close in around her. Against Impassable Barriers the fourth book in The Travels of Scout Shannon series, a young adult science fiction novel for fans of resourceful heroines, survival in extreme environments, girl assassins and loyal dog sidekicks.