A sharp scream echoes in the silent night at a Catholic girls’ high school. A fluorescent stick rolls on the ground and throws a light on Unjoo’s bleeding face. Her body is splattered on the ground. Her glaring eyes blink blood then the dead emptiness overshadows them. Strange rumors start to spread the school about Unjoo’s suicide. Unjoo’s younger sister Jung-un who attends the same school gets suspicious about Unjoo’s death. She tries to find out the truth by questioning Unjoo’s friends Soy, Euguene, and Eun-young who were said to have been with Unjoo before her death. Soy, who had been friends with Unjoo since junior high, denies her close relationship with Unjoo. Eugene tries to console Soy who’ in remorse, but she herself is tensed up. Eun-young keeps witnessing Unjoo’s ghost around the school and is utterly terrified. She tries to persuade Eugene to confess what they had done, but Eugene only treats Eun-young like a mental case. Eun-young starts to lose her mind at being haunted by Unjoo’s ghost. She ends up committing suicide just like Unjoo. After persistent investigation, Jung-un finds out that on the night of the incident, Soy, Eugene, Eun-young, Unjoo, the four of them had tried to commit a joint suicide after making a vow on blood. But the three are still alive, and only Unjoo had died. The desire, jealousy, and lies behind the pledge of death between the four girls are revealed, along with the hidden truth behind Unjoo’s suicide. 
(KoBiz)