Mild-mannered and modest Sook-young looks like your usual middle-aged woman, but happens to be a man-killing murderess. On a train trip to Mokpo, she remembers an earlier trip as a prisoner on furlough accompanied by a menacing but kind butch female guard. On the train they meet Hoon, a young man who falls for Sook-young. The guard lets them be alone at a bizarre marriage in a hill-top graveyard.

Crime ring leader Lee hires prostitute Seon to kill his subordinate Seok-gu who has threatened to take his place. Seon tempts Seok-gu to go to Mountain Seorak to assassinate him. But she falls in love with him in the journey and confesses everything to him. In fact, they have been shadowed by the spies Lee sent and bloody fight breaks out. Seok-gu in the end defeats all the villains.