Modern lawyer Chen Yan accidentally time-travels to Daasheng, becoming a utility worker in the Qingshui County yamen. Ordinary people here suffer injustices but have nowhere to file complaints; they cannot read or write complaint petitions, and verbal accusations alone make it hard to overthrow evildoers. Chen Yan picks up the law again, setting down case-solving principles: every lawsuit must present physical evidence, and empty words stand for nothing. IOUs, contracts, and fingerprints can all serve as evidence. He takes the farm girl Su Luming as his apprentice, teaching people how to write petitions and reason with evidence. As old case after case is cleared up, local strongmen and corrupt officials successively surface. The small lawsuits of Qingshui County wind up involving the prefecture's archives all the way, ultimately shaking the imperial court.