The entire Qin clan is exiled to Windblown Sand Fort after losing a border city they were tasked with defending. All they receive are scraps of cloth, dried thorn branches, and half a barrel of bitter water. Qin Zhiwu discovers that the cloth can catch the wind and collect water, while the dried thorns can be fashioned into windbreak fences to keep out the sand. Starting with nothing, she builds a cloth water-collection station and a water facility. She establishes rules, assigns tasks, and keeps accounts, transforming her clan from a disorderly group fighting over water into an organized, cooperative community. When merchant caravans hear about their water supply, they begin trading goods for water, turning the supposedly lifeless fort into a thriving hub along the trade route. However, the well operators and military supply officers repeatedly suppress her, accusing her of illegally establishing a private water station. From her father's belongings, Qin Zhiwu discovers half of a seal and an old defensive map. Combined with old caravan receipts, these clues reveal the truth about the supplies that were intercepted years ago. In the end, military and government officials publicly audit the accounts, corrupt officials are brought to justice, and the Qin clan's grievances are finally redressed. The clan is officially recognized as the Guardians of Water.