Cho Gwan Woong (Lee Sung Jae) who was born the lowest of class and was looked down upon by the people, managed to turn his desperate life around after getting first place in the military scholar exams. Blinded by his ambitions and greed for power, he caused the death of Minister Yoon and brought downfall to the Yoon family when he falsely accused them of treason. Yoon Seo Hwa (Lee Yeon Hee) who was sold as a gisaeng to Chun Hwa Gwan, escapes with the help of Chun Soo Ryun (Jung Hye Young) and her maid (Kim Bo Mi) when she learns that her enemy, Gwan Woong has his eyes on her.
Seo Hwa & the guardian god of Jiri mountains, Gu Wal Ryung (Choi Jin Hyuk) met and fell in love when she ran to hide out in the mountains but Gwan Woong soon catches wind of her whereabouts and comes hunting for her once again. Feeling unable to raise her son while escaping along with the fact that Wal Ryung has disappeared as well, she sent him down the river in basket hoping that someone could take him in. Meanwhile, Wal Ryung who has lost all his memories began to serve under his enemies as their underling. The only thing that will make the normally amnesiac expressionless Wal Ryung goes in frenzy is whenever he gets to hear Seo Hwa's name.
Choi Kang Chi who grew up with the Park family after he was picked up from river by Park Moo Sol (Uhm HoSub), the father of Park Kyung Jo (Lee Yoo Bi) and Park Tae Soo (Yoon Yeon Seok). Although Park Tae Soo used to treat him like a brother when they were younger, he started to feel a strong hatred towards Kang Chi when he misunderstood that Kang Chi is the main cause of the downfall of his family while Park Kyung Jo who always looked on him began to make use of Kang Chi to pave her way back to the noble status that her family once held after she was sold as a gisaeng to Chun Hwa Gwan and fate leads Kang Chi to meet up with Chun Soo Ryun, the head Gisaeng twenty years later after she encountered his mother.
Dam Yeo Wool (Bae Suzy), the daughter of Kang Chi and Tae Soo's teacher is one of the instructors of the martial arts school and despite her young age, Yeo Wool is highly skilled in archery. Although the cross-dressing Yeo Wool is always clashing with Kang Chi because of their different personalities, they find themselves falling for each other as they got to know each other better. Kang Chi soon discovers that he is actually a half-man and half-beast when his special abilities began to show after he goes after some criminals and to become a full human, he needs to find the Gu family's book to find the way to become one. When Kang Chi sets off on journey to seek his humanity, he ended up confronting his greatest enemy of his life, his father who never aged nor knew about his existence.