The Ferrymen - The Culling, #3

Torn in two directions, Glade must make one fateful choice-for herself, and the future of humanity. Glade Io is a rebel. Having fled with her younger sisters to live among the Ferrymen, she knows there is no going back now. She is committed to the cause of overthrowing the brutal Authority, and she trains her new comrades in the art of combating Datapoints like herself-those tasked with the Ferrymen's destruction.
Meanwhile Ferryman leader Kupier longs to travel the stars with Glade, free from constant war, but to do that he believes they must strike The Authority at its heart: the ancestral homeworld of Earth.  Glade is hesitant; she hopes taking out the Datapoints living on the Station will be enough. But when the time comes, Glade faces the specter of killing her former friends in cold blood and her former mentor, Dahn Enceladus, tells her that The Authority has eyes and ears within the rebel stronghold.
Now Glade faces a dilemma: sabotage The Authority from within, or return to fight alongside the Ferrymen, possibly putting her sisters' lives in danger.