Chae-Ryeong (Ko Jung-Min) calls her friends for a reunion. She hasn't seen Yeong-Hwa (Shim Yi-Young), Seon-Ju (Shin Dong-Mi) and Su-Hee (Min Ji-A) in 15 years. A few days later, Chae-Ryeong is found dead. Her three friends are the last to see her. Did she kill herself or was she murdered?