Yong-Nam (Cho Jung-Seok) graduated from a university several years ago, but he is still looking for a decent job. His hobby is rock climbing, which he was an active participant in his university days. Meanwhile, Yong-Nam's mother Hyun-Ok (Ko Du-Shim) is set to turn 70-years-old and she will have a birthday celebration at a convention hall. At his mother's birthday celebration, Yong-Nam sees Ui-Joo (Yoona). She works as an assistant manager at the convention hall. Back in their university days, Yong-Nam and Ui-Joo were members of the rock climbing club. Yong-Nam confessed his feelings for her back then, but Ui-Joo rejected him. To this day, Yong-Nam still holds feelings for Ui-Joo. Suddenly, a lethal gas spreads throughout the area.