Gregor and the curse of the warmbloods

With two prophecies fulfilled, Gregor is now focused on the Prophecy of Blood, which calls for Gregor and "the princess" Boots to return to the Underland to help ward off a plague. When they arrive in the subterranean city, the plague is spreading - and one of Gregor's companions is stricken. Only then does he understand his role in the prophecy. He must summon all his power to end the biological warfare, or the warmblood creatures of the Underland will die. - Back cover.