Choi Kang Chi is a half-beast and half-human and was adopted by a merchant Park Mu Sol when he was a infant. Kang Chi has a kind of unusual power. Dam Yeo Wool is the daughter of Dam Pyeong Joon who is the owner of the Invisible Knife Moo Kwan and also a patriotic warrior. Kang Chi and Yeo Wool meet and fall in love with each other. However, there is hatred between their fathers. Jo Gwan Woong is a traitor. He uses his power to frame faithful and upright individuals and obtain profit for himself. His criminal plots are destroyed by Kang Chi time and again. Therefore, he is determined to kill Kang Chi through different ways. Kang Chi is troubled by his identity but stands up for justice.