Incarceron is a prison unlike any other: Its inmates live not only in cells, but also in metal forests, dilapidated cities, and unbounded wilderness. The prison has been sealed for centuries, and only one man, legend says, has ever escaped.
Finn, a seventeen-year-old prisoner, can't remember his childhood and believes he came from Outside Incarceron. He's going to escape, even though most inmates don't believe that Outside even exists. And then Finn finds a crystal key and through it, a girl named Claudi