Who is the murderer in the script?

The fourth day of the month is an auspicious day, suitable for marriage. Mo Li, the monarch of Chizhou, will marry Jiangling, the only daughter of the late king, which is a great event in the world. On the wedding day, the bride disappeared and the monarch's maid died in her new dress. Ten years, one game, brothers turned against each other, my late king died suddenly, and the princess who had been missing for three years returned to the motherland. Is it a smile of gratitude and resentment, a marriage, or a careful plan to fight for life and death.