Gregor and the Code of Claw (The Underland Chronicles 5)
Everyone has tried to keep Gregor from seeing The Prophecy of Time, because the final prophecy calls for the warrior's death. Gregor must defend Regalia and get his family back home safely, but this won't be easy, because an army of rats is following him, and time is running out. There is a code that must be cracked or all will be lost. It is a war designed to end all wars.