In this chapter, Zhengzhou introduces us to Biyuancheng, who has come to the imperial kitchen to learn about medicine. He asks for water, a knife, and white silk, but Zhengzhou refuses to tell him what he needs. He tells Biyuan to rub the water over the white silk's and the secret report's fingerprints, and then he'll mix the water with the shavings of dangshan rock to make clear the differences in the colors of the two documents. Biyuan is shocked to find that the fingerprints on her white silk turned grey, while the ones on the report turned blue. Zhengzhou explains that he was preparing a daikon peony when he came into contact with the white vinegar. The person who framed him first sabotaged his ingredients, then framed him, and finally set him up for the stealing of the military report, but because they didn't understand the properties of the food, they were foiled. The royal brother is convinced that Biyuan was framed, but how will he prove that he did not take the report before handling white vinegar? Zhengzhou asks for an apology from Biyuan, and she agrees to share the burden.