Finn has lived in Incarceron for as long as he can remember... almost. He's one of the tremendous prison's many, many cellmates - one the others think was actually born from the ever-recycling Incarceron. But Finn and Gildas, one of the prison's Sapienti Wise, don't think so. His dreams and seizures can only point to a life Outside Incarceron.
Claudia Arlexa is the daughter of the Warden of Incarceron. Trapped in the sterile Era of their world, Claudia is doomed to an arranged marriage, planned her entire life. But, of course, Claudia is having none of that. What she wants to do is find Incarceron - even if her father is the Warden.
Cliché novel? It sounds like it. But rest assured, it is not. Both worlds - that of Incarceron and of the Era-world - are original and exciting. While more description could have been used at times to describe these fresh settings, what Fisher gives gets the reader by.
The book's pinnacle and downfall are its characters. Yes, they're both. Finn and Claudia seem like stereotypes at first, especially Claudia. But they show different, deeper sides I rarely see in other novels. Also, Gildas, Keiro, Attia, and Jared (my personal favorite) are all flawed, all too human, all too likable characters. Gildas is obsessed with the legend of Sapphique (supposedly the only man to escape Incarceron), but he really does care about Finn, even though it seems at times he uses him. Jared, a Sapienti on the Outside, is intelligent and wise, and daring to a degree, but he's a self-admitted coward. And yet you love just about every single person.
And yet... they feel cardboard. You're not really feeling what they're feeling; you're seeing it narrated. So perhaps Incarceron's downfall isn't it's characters, really. It's the writing. Crisp and to-the-point, it's amazing for the action; for character development, not so much. It's not that we don't get character development. It's just... hard to feel it. If you didn't already like the characters from reading about them, then I doubt many people would really care.
The ending is... different. The revelation of Incarceron's secret isn't a smack-your-forehead, I-should-have-gotten-that kind of revelation. It's more a wow-that's-a-really-interesting-idea kind of revelation. In short, there's not much real foreshadowing involved. Unless you're an in-depth scientist, I doubt you'll guess. This could be a good thing, or a bad thing, depending on your taste.
All in all, Incarceron wins. There's also a sequel, called Sapphique, coming out December 28, which I will be getting my hands on as soon as possible.