In ancient China, Emperor Yang is a tyrant who executes his ministers and neglects his people. Li Yuan, his loyal cousin, refuses to rebel against him until Emperor Yang's actions become unbearable. Li's son, Li Shimin, advises his father to raise an army against the emperor. After a successful revolt, Li Shimin becomes the Crown Prince of the new Tang Dynasty. As Li Shimin becomes more powerful, his relationship with his older brother, Li Jiancheng, deteriorates, leading to a deadly conflict.