Two North Korean soldiers are killed in the border area between North and South Korea, prompting an investigation by a neutral body. Sgt. Lee Soo-hyeok (Lee Byung-hun) is the shooter, but lead investigator Maj. Sophie E. Jean (Lee Young-ae), a Swiss-Korean woman, receives differing accounts from the two sides. Lee claims he fired in self-defense after getting wounded, while a North Korean survivor says it was a premeditated attack -- leaving Jean with her work cut out for her.