One day, a girl named Young-eon gets killed by a mysterious voice. After her death, her best friend, Sun-min, starts to hear Young-eon's voice. Although Sun-min is frightened at first, she decides to help her friend solve the mystery of her death. But she is not the only one who hears Young-eon's voice. A girl named Cho-ah also claims that she hears Young-eon's voice... and someone else's...

(Source: http://www.koreanfilm.or.kr)