A woman is found dead and her friends are suspected of the murder. Her name is Chaeryung. She dies under suspicious circumstances in her home. The police point to her high school friends, the first witnesses on the scene, as suspects. As the detective learns of an incident that took place 15 years earlier, he tracks down Chaeryung’s friends to determine what their possible motives might have been. The four women have suffered a great deal of anguish and pain, which later turns to hatred for one another. Who could have murdered Chaeryung, and why? A shocking truth is unveiled as the murderer is revealed.