Amor prohibido

The Gumiho Tribe has been living among humans in secret. While they have been consuming liver from human corpses for sustenance so as not to harm living humans, some began to resort to organ trafficking to acquire fresh human liver for consumption. Amidst this internal conflict within the tribe, Min Woo, a police detective at the Major Crime Investigation Division, raids an organ trafficking ring and encounters the Gumiho Tribe for the first time.

Si Yeon fails to assassinate Min Woo for witnessing the Gumiho Tribe's warriors in action when she sees that Min Woo is wearing a pendant that is identical to hers and assumes that he might be her long-lost childhood friend. While Min Woo continues to investigate what he saw on the night of the raid, he once again meets Si Yeon at the museum where his sister is working by chance, and feelings begin to develop between Min Woo and Si Yeon.

The Gumiho Tribe is met with internal conflict after it is revealed that one of their elders was involved in the trafficking of fresh human liver. SICS, a secret government organization that has long been after the Gumiho Tribe, contacts Min Woo and asks him to join them as their agent. The leader of the SICS tells Min Woo that the Gumiho may have been the ones who murdered his parents.

Min Ju, Min Woo's little sister, prepares to set Min Woo and Si Yeon on a blind date unbeknownst to them. Internal conflict within the Gumiho Tribe grows as the elders plot against their chieftain to reduce her power within the Elders' Assembly. Elder Nam witnesses Si Yeon as she is leaving the scene after assassinating Elder Kang, who was involved in organ trafficking.

The SICS raids the hotel room where Elder Kang is hiding in an attempt to apprehend her. However, they arrive too late and find that Elder Kang has already been assassinated. Unrest within the Gumiho Tribe's Elders' Assembly grows as Elder Nam alerts the other elders of what he saw regarding Elder Kang's assassination. Si Yeon decides to visit Elder Nam to tell him that she didn't kill Elder Kang.

More elders are assassinated, and the distrust between the elders and the chieftain grows, prompting Elder Nam to visit the chieftain to deliver his ultimatum. Min Woo meets with Moo Young and learns that Si Yeon lied to him when she told him she would soon be wed. With this, Min Woo confesses his feelings to Si Yeon.