Kingdom of Cages follows the lives of one family: Helice Trust (a single mother), and Chena and Teal Trust, her daughters. This family is teetering on the very edge of survival on Pandora, the most Earthlike world humans have ever discovered. The Pandorans are dedicated to protecting the ecology of their world by keeping it pristine and minimizing interaction between human ecologies and Pandoran ecologies.

The Trusts begin the book living in a space station orbiting Pandora, where they must pay for their air. When that becomes too much of a burden, Helice takes her daughters down to Pandora, where all three must toil at menial jobs in order to pay their way. Failure to pay or violation of any law has only one penalty: forfeiture of body rights. When that happens, the Pandoran government, organized by family, involuntarily commits offenders to biotech centers that experiment freely on them without concern for their physical or mental health.

Members of the ruling families are deeply committed to one another. This commitment is augmented by Conscience implants that dominate each individual's decision making processes. Family members cannot lose their body rights -- transgressions are handled by altering one's implants. The implants are
linked to an organic computer shared by all the family members that coordinates their lives and provides for long-term memory. All this takes place in a universe where human colonies are falling victim to a terrible plague -- a Diversity Crisis -- and the other colonies threaten to overrun Pandora, and violate the planet's delicately balanced eco-system.

All these details are revealed on the dust jacket or in the first chapter. The conflicts in this book are multi-layered and cross-cutting, and Zettel handles them with great subtlety, interweaving the personal and political story lines deftly.

Thematically, the book is quite similar to the two other Zettel books I have read -- _Playing God_ and _The Quiet Invasion_ -- and has a very "Ayn Rand" feel to it. On the one hand, a communal society with consciousness-sharing abilities is trying to protect its own existence, while on the other, an individualistic society which cannot control rogue members is threatening that existence. This book handles these conflicts far better than the other two, and articulates the philosophic distinctions between them with great clarity.

However, the book does not live up to its potential. It is 608 pages in paperback, 496 pages in hardcover but it is still too short. This really needs to be a BFB or a series as Zettel fails to follow through on several subplots and fails to solve the substantive problem in the book, the Diversity Crisis. Beginnings are made, personal relationships are healed, and short-term crises are solved, but huge questions are left dangling and there is no internal or external evidence that Zettel plans a follow-up. As it stands, the book is incomplete and the ending is unsatisfactory. However, it is interesting enough that I am glad I read it, hence my '0' instead of '-' rating.