A former fresh-produce quality inspector returns to his hometown carrying 400,000 yuan in debt. He starts by helping a vegetable seller sort 300 jin of unsold Chinese cabbage into three grades for sale, gradually opening up restaurant supply channels through cut surfaces, grading labels, and tastings. When competitors slash prices, customers are poached, and prolonged rainy weather causes supply shortages, he relies on quality control and advance orders to weather every setback. From a single grading chart to a standardized system adopted across an entire street, he manages to repay most of his debt. His mother hands over her tofu stall, and someone finally takes over writing in his father's old account book.