While patrolling the northern regions in Joseon, Prince Lee Bang Won encountered and sealed away an evil spirit who wanted to dominate human beings.
Bang Won helped his father found the Joseon Dynasty, and later became king himself under the title Taejeon. He is proud of what he has accomplished, but deep in his heart he felt guilty that he had killed many people for this. The evil spirit, which he had sealed away so long ago, now manifests itself, forcing the king to battle his nemesis once again.
Taejong’s eldest son, Crown Prince Yangnyeon (Park Sung Hoon) looks confident, but in fact has constant anxiety, and he does not live up to his father’s expectations. Consumed by greed and a need for power, Yangnyeong chooses to enter into a contract with the evil spirit.
Prince Cheonnyeon (Jang Dong Yoon)is the younger son, whose only interest in life has been the pursuit of academics. Faced with the crisis caused by the evil spirit, he must now wage war against the entity, in order to protect the people.
Also known as: 조선구마사 Joseongumasa Chosun Gumasa / Chosungumasa/ Joseon Gumasa