''Let your emotions flow... like water''

Joseon is in the middle of a big protest, which was started by the people. The king is quite heartless towards the people and just let the poor people die, while only caring about the money. But the king's biggest enemies are those who can bend the four elements: Water, Fire, Air and Earth. The king has given a lot of orders to get these elementbenders killed, but he fails time after time. His only son Hakyeon is friends with Jung Taekwoon, who is a water bender. Hakyeon is still in charge of being the crown prince, but the king still thinks that his only son isn't capable enough to rule over the kingdom. In the mean time, anger is boiling up inside the elementbenders and all want to take down the king and see the crown on someone's head who is able to bring peace to both the people and the elementbenders. When the king hears about Taekwoon's skills, he becomes more and more convinced that Taekwoon might be the best successor. But when Taekwoon is being brought in to assign him the official title of crown prince, things start to change between Hakyeon and Taekwoon. Taekwoon only has one job: to bring peace to Joseon and to bring peace to both the people and the elementbenders...