Echoes of the Self Episode 19

During Fu Wei and Li Yan's wedding, Li Shu accuses Fu Wei of being an impostor and demands a search of the Yan Prince's residence. Although the real Princess of Daqing is not found, a secret letter exposing Li Shu's unauthorized actions is uncovered instead. Enraged, the emperor places Li Shu under house arrest, clears Fu Wei of suspicion, and allows the wedding to continue. That night, Li Yan and Fu Wei finally become husband and wife. The next day, several senior officials petition to replace Li Shu as crown prince with Li Yan. However, Li Yan refuses to support the proposal, believing it would only destabilize the court. Later, he visits Li Shu, but their meeting ends in another argument, which Zhou Ruo Xi secretly witnesses. Acting on Zhou Kui's orders, Zhou Ruo Xi secretly drugs Li Shu with Xiaoyao Powder to bring him under their control. (Source: Chinese = tvmao.com || Translation = KamilaRN at MyDramaList)