21-year-old Ryu Yeon-seong is set to begin his mandatory military service in the ROK Army. However, unlike most other conscripts, he and four others are assigned to the mountain police rescue unit stationed at Mt. Bukhan, a small mountain on the outskirts of Seoul. Unfamiliar with the role, they assume it will be easy and consider themselves fortunate to have secured such a comfortable posting. But upon arriving at the mountain, the group soon realizes they are in for more than they bargained for.