A single false accusation sends dozens of members of the Jiang family from their grand residence in the capital to the desolate lands of Qianzhong, three thousand li away. Everyone believes this exile is a one-way journey to the underworld, but Jiang Zhao sees something different: mountains filled with coal, iron, salt, and cinnabar. This is no exile. It is a gold mine that no one has recognized. The authorities give her three months to smelt fifty thousand jin of military-grade iron at the abandoned furnace. If she fails, her entire family will pay with their lives. Using black stones from the mountains as fuel and harnessing a stream near the valley to power the bellows, she brings a furnace that has been dead for twenty years back to life in just five days. From then on, she builds one furnace after another, smelts iron, reclaims wasteland, produces salt, and mines cinnabar. She wins over the furnace workers, comforts displaced refugees, and joins forces with frontier generals to defeat bandits and secure the border.