Missing and death cases take place in succession along the Korean Demilitarized Zone. South Korea forms a unit led by Captain Jo Jin-Ho and First Lieutenant Shin Yoo-Hwa as assistant leader. They are given only 24 hours to find out the truth behind the incidents. Team members find evidence, but they feel like something isn't right.

The border of 820 is where the North and South Koreas stand face to face. Elite female lieutenant Kwon Jin-kyeong from the Korean Military Academy and 4 other cavalry battalions are on patrol on their last day of training. Meanwhile, students from the photography club get lost on their way to check out scenery and enter BAse 820. An unknown shot is fired and the group is terrified. Kwon Jin-kyeong and her team look for the source of the shot...