GP is the sentinel of the non-military zone at the front line of the ceasefire line, a remnant of the post-Cold War era. On a rainy night in May 2007, all 20 members of GP506 were killed by a single soldier. Due to the fact that the captain of 506 is the son of the Chief of General Staff, the military was highly anxious about the incident and dispatched investigator Lu (played by Choi Ha-jin) to uncover the truth in one night. The search team entered the guard post where 506 was stationed that night. Aside from the surviving suspect soldier, Jiang Chun-yuan (played by Lee Young-hoon), there was one body missing from the expected twenty. The search team discovered a survivor who claimed to be Lieutenant Ryu, the captain of 506 (played by Jo Hyun-jae), who was in shock and refused to disclose any details about the incident. However, heavy rain blocked the roads, and Lieutenant Ryu, unable to leave the guard post, had to recount the hidden truth of the infection among the members of platoon 506. It turned out that some members of the squad had contracted a mysterious infection that made them extremely aggressive. To protect his career, the captain refused to report it, leading to a mutiny among the troops and ultimately, the massacre...
Horror
