Originally published in hardcover by Scholastic Press in 2007.

Everyone has been trying to keep Gregor from seeing "The Prophecy of Time". That is because the final prophecy calls for the warrior's death. With an army of rats quickly approaching and time running out, Gregor must defend Regalia and get his family back hom safely. There is a code that must be cracked, or all will be lost. It is a war designed to end all wars. The fates of the Underland and the great warrior, Gregor the Overlander, masterfully unfold in this final installment of the Underland Chronicles.