This is the sequel to Sagan's Idlewild, and I confess I'm not sure what to make of it.
It begins about 18 years after the conclusion of its predecessor. The human race has been all but destroyed by the Black Ep virus; the only survivors are Halloween and five others, and the children they have since brought into the world. Their chief goal (indeed, their reason for being) is to find a permanent cure for Black Ep and then repopulate the world. But Halloween and his age-mates didn't have what you'd call a normal childhood with a stable home-life, and raising children is a tricky business indeed. Most of the kids are doing OK, having normal adolescent angst, but one or two of them, well...
In fact, that's probably the best way to describe this book--it's about parenting, and how to raise sociopaths. As such, I don't find it entirely convincing; the proportion of truly amoral people in this book seems to me to be a little too high.
There's an interesting note on the effect of a religious upbringing. Five of the kids are raised in the Sufi tradition (Sufi is a mystical branch of Islam). The most stable kid in the whole bunch is one of these; he's also the most devout. He's balanced by his two older brothers, who had the same upbringing; one abandons his faith for atheism and the bright lights, while the other abandons Sufism (Sufiism? Sufi-ism?) for a more literal reading of the Koran and becomes mightily annoying to all around him.
On the whole, I don't think I like this book as much as its predecessor. It takes a while to get started, and it's less convincing. Moreover, the point I draw from it--that kids need a moderate, firm level of discipline, giving them neither too much nor too little freedom of choice and experience--seems obvious to me. But then, I grew up in a functional family.