Much to his parents dismay, Kim Jungwoo decides to fulfill his dreams of leaving Seoul to study abroad in New York City. The first few days in the new city are fairly pleasant. But all good things come to an end when he falls victim to an assault robbery and his savior, Lucas, presents himself to be more than an average human. Lucas is a creature of the night, a vampire with centuries of blood on his hands. Jungwoo becomes oddly drawn to the vampire and befriends the lonely beast, which opens a gateway to the worlds of angels, demons, spirits, and other supernatural beings. 

The unusual pair embark on missions to save the innocent from evil entities. But when the friendship starts to blossom into something more, Lucas knows he must not allow Jungwoo to get too close. If he lets the young man in, the curse will re-awaken and make him revert to his rogue, sadistic past of terrorizing the world once again as Osiris.