Mute Moon-young records people's faces with her small camcorder on the subway. One day, she avoids her drunk father at home and films Hee-soo who is crying over saying goodbye to her boyfriend and gets caught. The two feel some sort of kinship and become closer.
The four high school girls, each of whom has their own personality and appearance, happen to witness the four twins' suicide while preparing for the choir competition.
Ha Yoon-ju becomes the newest member of a unit within the Korean Police Forces Special Crime Department that specializes in surveillance activities on high-profile criminals. She teams up with Hwang Sang-jun, the veteran leader of the unit, and tries to track down James who is the cold-hearted leader of an armed criminal organization.