The Princess Royal Episode 38

Su Rong Qing pours a cup of tea, wipes its rim with his thumb and offers it to his father. His father becomes blind and mute after drinking the tea. Su Rong Qing calmly tells his father that if Su Family wants a prosperous and wealthy lifetime, they have to support a king who listens to them. He then takes away his father's token and tells him to have a good rest. Su Rong Qing gives the order to lock up his elder brother once he is found. He then waits for Li Chuan to take action. Meanwhile, Pei Wen Xuan retrieves his family token from his second uncle. Li Rong leaves the city. Shangguan Ya stops her and tells her that Su Rong Qing has rebelled. (Source: Chinese = Baidu || Translation = AnastasiaWun at MyDramaList)