Shen Zhiyi, a modern audit manager, unexpectedly transmigrates into the body of the Shen family's foolish second daughter and is forced to marry into the Lu family, which is on the verge of bankruptcy, in place of her runaway older sister. On her wedding day, she stumbles upon a conspiracy to burn account books and silence a witness. From a dead man's private seal, she uncovers fraudulent accounts worth 3,000 taels. Facing relentless pressure from the Pei family's money shop, business guild monopolies, and false accusations planted by a traitor within, she relies on her auditing expertise, contracts, and business acumen to join forces with Lu Cheng'an. Together, they establish a transport fleet, expose scams, and restore trade routes. In the end, she uncovers a long-buried case and makes everyone who underestimated her pay the price.