After Cheon-ji’s unexpected suicide, her mother, Hyeon-sook, and older sister, Man-ji, are forced to move into another apartment and face the shock left behind. Unable to let the loss remain unexplained, Man-ji begins tracing clues connected to Cheon-ji’s school life. Her search gradually leads her toward Hwa-yeon, Cheon-ji’s best friend, and the painful questions surrounding her death.