Inspection of the plot Ministry of Public Security Inspector Gangmun-gil is enjoying a picnic with his family on holidays. He wakes up in a nearby neighborhood where he picks up rusty shells from nearby Kangdongsan and witnesses a devastating explosion. The family members of the Kang test who have not escaped from Seoul are caught by the Communist army. Even at the end of all torture, his wife, Shinhee, does not cover the area where the river exam is hidden. However, the spy Choi Choi, who was sentenced to death, does everything he can to find out the location of the river exam. The Kang test finds the importance of security with the people of all walks of life who have imagined the last moment when his family is put to death.