Nirvana in Fire Episode 42

Banruo and Xia Jiang open the pouch and find a letter written to Prince Yu, by his mother, Hua Princess Linglong. Banruo tells the prince of her discovery, making him believe that the Emperor wrongfully killed his mother as well as purposely stopped him from being the Crown Prince. Mei Changsu tells Mu Qing to release Wei Zheng for him, so that the ex-Chiyan general may talk to Prince Jing about the battle in Meiling 13 years before. Prince Jing learns of the whole truth, and resolves to reopen the case. Banruo uses Jun Niang to get information about Mei Changsu and the Poison of the Bitter Flame from Tong Lu. For the Spring Hunt, Prince Jing takes Mei Changsu and the Emperor to the retreat, leaving Prince Yu in the capital to instigate his own plan. Consort Jing asks to see Mei Changsu. (Source: Wikipedia)