The film revolves around the relationship between two high school students, Yoo Shi-Eun (Lee Young-jin) and Min Hyo-Shin (Park Ye-jin). As the two girls become romantically involved, their taboo friendship causes them to be marginalized by the other students. Unable to cope with the social pressures of having a lover of the same gender, Shi-Eun tries to distance herself from the increasingly dependent Hyo-Shin. Hyo-Shin reacts poorly to Shi-Eun's changed attitude, viewing it as both a betrayal and rejection. Hyo-Shin consequently commits suicide by jumping off of the school roof. It is also heavily implied that she was pregnant at the time of death, the father being literature teacher Mr. Goh.