Chu Zheng, a construction supervisor, trusted the local building materials dealer Sun Mei for three years, only to unexpectedly discover that she specialized in exploiting familiar customers by selling inferior yellow sand at inflated prices. Deeply disappointed, he abandons the monopolistic supplier and chooses the siblings Lin Fan, who have opened a new sand yard and remain committed to their principles. Enraged by the loss of business, Sun Mei resorts to malicious schemes, deliberately swapping building materials and filing false reports to frame them. Relying on strict regulations and irrefutable evidence, Chu Zheng exposes her despicable conspiracy, safeguards construction quality standards, and establishes a new culture of honest business and rule-based conduct in the town.