The premise is... *ahem* Actually, I'll read the back cover:
"The Second Civil War was fought over reproductive rights. The chilling resolution: Life is inviolable from the moment of conception until age thirteen. Between 13 and 18, however, parents can have their child 'unwound,' whereby all of the child's organs are transplanted into different donors, so life doesn't technically end. [this is set in the future, so 'science' makes that legit.] Connor is too difficult to control. Risa, a ward of the state, is not talented enough to be kept alive. And Lev is a tithe, a child conceived. and raised to be unwound. Together, they may have a chance to escape- and to survive."
Sounds weird (and probably kinda stupid), right? Everything makes sense as you read, trust me. It's a good read.