As Old Li lies dying, he divides the family property, giving cash and a new house to his eldest son while leaving an old, dilapidated cave dwelling and an ancient jar of fermented sour water to his second son, Li Jianguo, forcing him to swear never to dig it up for three years. Li Jianguo and his wife honor their oath and endure life's hardships, gradually improving their circumstances through growing medicinal herbs. The eldest son, burdened by debt, brings outsiders to forcibly excavate the land, but villagers and police intervene to stop them. When the three-year period ends, gold bars and Western Zhou bronze artifacts are discovered inside the jar. A notarized will clearly establishes that they belong to Li Jianguo. He voluntarily turns the national treasures over to the state and, after receiving recognition, leads the villagers in developing local industries. His greedy elder brother and sister-in-law are also punished for their wrongdoing.