Secretly, Greatly

Secretly, Greatly(은밀하게 위대하게) is a 2013 South Korean action comedy-drama film starring Kim Soo-hyun, Park Ki-woong, and Lee Hyun-woo, who play North Korean spies who infiltrate South Korea as a village idiot, a rock musician, and a high school student, respectively. They assimilate to small town life while awaiting their orders, until one day, due to a sudden power shift in the North, their mission turns out to be an order to commit suicide.

The film is based on the 2010 spy webtoon series ‘Covertness’ by Hun, which has received over 40 million page hits.

Plot

A group of spies called the 5446 Corps were trained by North Korean special forces since their youth, ostensibly towards the lofty goal of unifying Korea. They are ambitiously dispatched to South Korea, where each disguises himself as a fool, an aspiring singer, and a high school student. Passing boring time without receiving any orders from the North, they gradually get used to life as ordinary neighbors in a small town until one day, their mundane lives are turned upside down when a "secret and great" mission is suddenly assigned to them, it turns out to be an order to commit suicide to prevent the elites from falling into enemy hands, the North Korean government orders dozens of active duty spies to take their own lives. However some of spies don’t obey the order while asking government to ensure safety of their families. Meanwhile, their North Korean army instructor Kim Tae-won crosses the border to eliminate those who refuse to follow.

[Reference : Wikipedia]