The emperor believes the lingzhi is magical and when it suddenly starts to wither, believes the Grandmaster's message about something bad in the palace. Ye Jun Qing is ordered to investigate and finds fake medicine. Then he finds the dead bodies of maids who tested the fake medicine and died. Yao Mo Wan interrogates the criminal to learn about the gunpowder smuggling. She also learns that the emperor was indeed the one who caused her sister's miscarriage. The official couldn't find any evidence of Dou's crime, but Ye Jun Qing brings evidence of their crime from smuggling gunpowder. Ye Jun Qing sends the kind of thieves to find the incriminating ledger. (Source: jindreame at MyDramaList)