Like a few other small communities, the residents of Glenrock have managed to live peacefully outside the nearby Safe Lands for quite some time. Their existence is quite archaic compared to the posh lifestyle offered within city walls, but those city dwellers suffer from something the outer communities don't - infection via the thin plague, which has completely ruined their ability to reproduce. So it's not surprising when Glenrock is invaded and their women, children, and young men are taken at force, and their elderly killed off (because in the city's eyes, all people should be liberated (ie. put down) by the age of forty.)
Only one young man wasn't present for the invasion, and after failing to acquire help from the other communities, sets off with the delusion of being able to save his people and his bride-to-be. It's not long before they're all captives and forced to assimilate to city life or be put down themselves. The women are forced into a surrogacy program and the men forced to donate their sperm to impregnate them through in vitro fertilization. Disgusted with their newfound fame, with the women in a harem that literally treats them like queens while a part of the surrogacy program, the residents of Glenrock are desperate to find cracks within the civilization and reclaim the freedom that is rightfully theirs.
What I like best about Jill Williamson's novels, is that although she writes Christian fiction, she neither preaches through her writing nor shoves religion down your throat. So if you're hesitant to pick up her novel because of this, don't be, because even though the religious undertones are there, you probably won't even pick up on them if your not religious yourself. Captives is a great dystopian novel about a greedy, self-centered society so corrupted and run by desperation that they can no longer see how immoral their lifestyle and actions have become. And the fact that it was one of their own that sold them out to the city to begin with? Priceless.