Shen Yanzhou returns in glory to Hangzhou with his wife Su Wantang, taking office as assistant prefect to tackle the local salt administration. Vice Magistrate Yuan Zhenhai rules with rampant corruption, embezzling salt taxes, brutally exploiting salt workers, while simultaneously trying every means to win over Shen Yanzhou and secretly plotting against him. Wise and daring, Su Wantang maps the real conditions of the salt fields under the guise of sketching, and unearths an old, dust-covered account book from home, uncovering the past story of how her grandfather died of pent-up grief due to the Yuan family's black accounts. Working as one heart, the couple visits salt workers to gather testimonies, and secures key account books handed over by the newly awakened Qian Muzhi. Through coercion and obstruction, everyone presents ironclad evidence in the official court, ultimately investigating and cracking Yuan Zhenhai's criminal case.