When Gregor and his baby sister fall into a hidden world beneath New York, they uncover a prophecy, a war, and a chance to find what was once lost - if they survive.
Gregor returns to a perilous underground world where a chilling prophecy threatens his sister's life - and the fate of an entire realm rests on his next choice.
As a deadly plague spreads through the Underland, Gregor must unite enemies and race against time to find a cure before all warmbloods - and his bond - are lost forever.
As war brews in the shadows of the Underland, Gregor uncovers a chilling genocide and a prophecy that may force him to kill the creature he once chose to save.
In a world on the brink of ruin, a boy fated to die must unlock a deadly code, face a monstrous enemy, and decide if destiny is stronger than his will to choose mercy.