With the Korean peninsula under threat from a devastating volcanic eruption, unlikely allies carry out a secret mission to prevent the disaster.

Busan, South Korea, 1970s. Lee Doo-sam is a small-time smuggler. After helping a drug gang to smuggle meth, he falls into the dark crime world. Quick-witted and full of ambition, he eventually takes over the drug underworld and starts to lead a double life: a good community leader during the day but an infamous drug lord during the night.

Two apathetic police academy recruits who become best buddies through the tough training together witness a woman being abducted right before their very eyes. As they were taught in the academy, they quickly report the incident to the police, but the police are in no hurry to jump on the case. So the duo decide to take the matter into their own hands and rescue the woman.