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.
- Genre: Mystery, Crime, Drama
- Studio: KBS2
- Keyword: high school, serial killer, school, slasher, psychological thriller, christmas, drug
- Cast: Kim Sang-kyung, Baek Sung-hyun, Kim Young-kwang, Lee Soo-hyuk, Kwak Jung-wook, Hong Jong-hyun