Detective Baek Hong Suk (Son Hyun Joo) is A father and a detective, he loses his daughter to a hit and run accident and loses his wife in the shock as well, so he sets out to find out the truth and stands against the center of authority
Kim Yo Han is a psychiatrist who gets involved in a serial murder when his car broke down on Christmas Eve during a sudden storm and he is forced to take shelter at a private high school. Seven students and a teacher are also there over the winter break, but they are gradually murdered one by one as they receive letters from a killer who wants revenge for the death of his mother and sister.
In the story, the gumiho leaves her husband and has a young daughter who has inherited her mother’s ability to shape-shift (gumiho lore includes their abilities to transform themselves to look human). She decides to take revenge against a human.
A terrorist group known as "Athena" and led by evil mastermind Son Hyuk threatens South Korea and the world. It is now up to special agent Lee Jung Woo of the National Security Agency to foil their terrifying conspiracy.
Gun Wook (Kim Nam Gil) plans a revenge against the Haeshin Group. A company to whom Tae-sung (Kim Jae Wook) is the heir.
Kim Hyun Joon is an assassin who belongs to a top secret organization known as the "NSS" whereas T.O.P is an assassin who works in another secret organization located in the United States called "IRIS" and was ordered to kill Hyun Joon. Seung Hee is a psychological analyst who plays an important role in bring Hyun Joon into the "NSS." Jin Sa Woo is Hyun Joon's enemy and falls in love with Seung Hee as well.
Behind the doors of Namwon Hospital lies a chilling secret, one that the hospital’s inhabitants have kept buried for the last 10 years, and all centered around one coma patient, Lee So-hee. With the hospital’s reputation steadily declining over the years, it is forced to shut down. Though as the hospital closes its doors, another opens, and secrets that have long been hidden are coming out with a vengeance.