It has been barely four years since the unfortunate train incident that had left two hundred people in great tragedy. The wounds were slowly getting fully healed by now, and yet Jung Eunji still feels very much incomplete. She barely remember anything from the shock four years ago, and her body somehow wishes that she won’t know. As she tries to look for answers, her boss decided to bring her to Seoul for a winter holiday along with his family. And there she meets a woman she could barely even remember the name of.