This movie is based on actual events. After North Korean commandos tried to assassinate South Korean President Park Chung Hee in 1968, the Southern Government set up a unit to kill North Korean President Kim Il Sung. The unit was made up of prisoners sentenced to death for various offenses. During their preparation, the South Koreans scrapped the idea; contrary to what is stated in the film, though, it is unknown what happened next, only that the unit eventually mutinied.
This film became the first movie to sell over ten million tickets nationwide in South Korea.