[1] Written by Park Yeon-seon and directed by Kim Yong-soo,[2] it aired as part of the Drama Special Series on KBS2 from January 30 to March 20, 2011 on Sundays at 23:15 for 8 episodes.

The drama deals with the question of whether evil is organic or environmental, and the potential for adolescents to be extremely empathetic as well as equally cruel.

Their stellar marks are the result of constant pressure and a strict punishment system, to the point where students avoid any activities outside of studying.

Park Mu-yeol (Baek Sung-hyun) is an honor student who chooses to remain in school during the winter break after receiving an abusive letter.

[3] At a time when everyone else is celebrating the holidays, the students realize that the anonymous letters they each received were not the result of a harmless prank; there is a murderer in their midst.