After taking Mount Grief at great cost, the Frontier Army receives a visit from an envoy of the dwarven Ironblood Kingdom, now imperiled by the orcs and undead of the Southern Expedition. When Jin Mogis learns the dwarves have been resisting the enemy with a new secret weapon, he decides to dispatch a delegation to negotiate with them. Chosen to be part of that delegation, Haruhiro and company cross the Quickwind Plains, contending with terrifying giants and dangerous beasts as they head toward the dwarven kingdom in the distant Kurogane Mountain Range. What awaits them at the end of their journey's twisting path—a negotiation, a decisive battle, or something else?! When the answer appears before them, everything will change!