The story follows Shen Wan, the daughter of Shen Yi, a high-ranking official of the Supreme Court, whose entire family is massacred after being implicated in the Prince of Jin case. Shen Wan escapes to Jingzhou by disguising herself as Qin Wan, the Ninth Lady of the Qin family. Once perceived as gentle and easily bullied, Qin Wan undergoes a "drastic transformation". She not only excels at healing the sick and saving lives but is also skilled in performing autopsies to investigate crimes. She even manages to subdue her manipulative aunt, stepsister, concubines, and cunning servants within the Qin household. During her investigations, Qin Wan meets Yan Chi, the crown prince of King Rui. Yan Chi is determined to clear the Prince of Jin's name, an ambition that aligns with Qin Wan's own mission to vindicate her father. The two return to the capital together, solving a series of strange and mysterious cases along the way. After returning, the discovery of a skeleton leads to the reopening of the Prince of Jin case. As they delve deeper, Yan Chi and Qin Wan gradually uncover the truth and ultimately expose a shocking secret buried deep within the palace.