Steel Rain is a Korean thriller movie, written and directed by Yang Woo-suk. It is based on the webcomic of the same name.
Retired North Korean agent Cheol-woo Eom is covertly contacted by his former boss, Chief Ri. Ri informs Eom that two senior functionaries (Park and Kim) are plotting a coup. Since the two men are highly placed and can keep Ri from alerting the Great Leader to the plot, Ri has no choice but to have both men killed.
Ri cannot use one of his subordinates for the job because if the operative fails, the assassination attempt could touch off an inter-service civil war. If Eom is caught, he can be thrown under the bus. Eom agrees to work for Ri one last time.
On a certain fateful day, Eom is in position, ready to kill Park and Kim. There are two problems. The first is that Park is not at the rally where Eom is waiting hidden with his rifle. The second is that agents unknown detonate several hijacked cluster bombs, bombs that kill most of the people attending and leave the Great Leader badly injured, perhaps dying.
Luck and skill get Eom through the attack unscathed, as well as the massacre of the few survivors that follows. Realizing a coup is underway, Eom and helpful cheerleaders Kwon and Song flee with the Great Leader into South Korea. Behind them, North Korea descends into chaos.