One year has passed since the Second Battle of Blackloc, the four heroes-Ganderian, Halamar, Hera, and Jack-have gone their own paths. However, when dark forces wage war across the Four Kingdoms, the heroes must work with new allies to protect their world, or risk perishing in the invasion... Hera Nighthart finds herself unwittingly cast in the middle of an invasion from nowhere, and forced to fight for her life. Rescued by Berabus the Warden, a wolven warrior chief who seeks to end the Skeite, she finds herself deep under the surface of Minterra, in the mythical Deepground Kingdoms. With newfound allies, the noble Dwargar Berdell Myden, and the suave Dokelvar Dallen Einar, Hera seeks to brave the dangers lurking in the darkness below in search of a path to the surface, before the Skeite leave the world above a scorching ruin...