Lin Weidong, a quality inspector at Hongxing Machinery Factory, stops Liu Changgen, a canteen worker of thirty years, from secretly taking braised pork out of the factory. Because he insists on inspecting the hidden compartment of Liu's lunchbox, the entire factory accuses him of being heartless and deliberately targeting a veteran employee. He is transferred out of the quality inspection department and banished to the warehouse. Enduring the public criticism, Lin secretly investigates and discovers that the lunchbox's hidden compartment conceals daily production reports from the workshop. Influenced by his son, Liu stole critical process data and colluded with an insider in the supply and sales department to leak it to an outside workshop, causing the factory to lose a major contract and suffer reputational damage. Lin gathers the complete evidence and reports it to the investigation team, exposing the entire chain of leaks. He establishes a rigorous filing and quality inspection system, safeguarding Hongxing Factory's technological foundation and the livelihoods of its thousand workers.