An assassin trained in the traditions of the Ruska Roma organization sets out to seek revenge after her father's death.

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.

Sang-hwan became a cop in order to help the downtrodden, but he doesn't get much respect. All that changes when he meets the Seven Masters.