Set in the 18th-century Joseon, it tells the story of Crown Prince Lee Sun and his fight against a powerful and wealthy organization Pyunsoo hwe, who controls the country behind the scenes. He becomes a hope for the people who suffer from lack of water due to the greed of Pyunsoo hwe, who tried to privatize the nation's water supply. With the help of the woman he loves, Ga-eun, Lee Sun overcomes adversity and grow as a just ruler.