Nirvana in Fire Episode 4

At the banquet, Mei Changsu asks the Emperor to allow him to use three servant children, including Tingshen, to battle competitor, Baili Qi. The Emperor agrees, as he did not want Mu Nihuang to be married to the Northern Yan. Meanwhile, Concubine Jing, Prince Jing's mother, meets Consort Fei, and offers to go with her to the deceased Empress Dowager palace to pay their respects to her. On their way back, they overhear a servant talking about Qing Si Rao, a strong concoction that knocks people out of consciousness. Later, Concubine Jing notifies Grand Princess Liyang about the wine and asks her to help its potential victim: Princess Nihuang. While training the three children, Mei Changsu meets Prince Jing and tells him that he will help him become the heir to the throne; Prince Jing agrees to form an alliance with him. That night, Liyang seeks help from Mei, asking him to notify the princess about the wine for her. (Source: Wikipedia)