Jin-il, [Minho], leads a small gang of four runaway youths who scrape by on odd jobs and petty crime. Ga-young, [Jeong Da-eun], decides to run a prostitution scam by luring men, and Jin-il and Bong-gil, [Lee You-jin], steal from the client. When she tests the scam on her first target, Hyung-suk has no interest in sex but offers to help young people like her by giving them a job in his karaoke bar, a front that quietly doubles as a space where underage workers are groomed for prostitution. The first attempt spirals into violence: Hyung-suk beats the two boys, but they overpower him and reclaim his car and wallet. Later that night, as they try to sell the car, Jin-il and Ga-young recognize and are recognized by the buyer Sung-hoon, Ga-young's former boyfriend who was jailed for murder but released early thanks to his wealthy family, after Jin-il tipped off authorities. They flee, narrowly escaping capture.
That same night, Hyung-suk tracks the pair down and abducts Jin-il and Ga-young. Under duress, after beating Jin-il, Hyung-suk forces Ga-young to sign a contract to work at his bar until the car is paid off—a debt Jin-il begins paying off by committing further crimes. Hyung-suk also tracks Sung-hoon, and confronts him to recover payment for Jin-il’s whereabouts. Sung-hoon, determined to know where Jin-il is, sends his own henchmen to locate Hyung-suk’s apartment and offers payment for Jin-il’s location.
In a separate sting operation, a failed scheme involving stolen cellphones (there were none) leads to Bong-gil being accidentally stabbed by his own knife and ending up in police custody after hospital release. Jin-il is arrested at the same time and, facing a mounting confession, tells the police that Hyung-suk’s bar is a front for a brothel that exploits underage girls. A police sting using Jin-il at the bar fails because Hyung-suk has removed Ga-young and pretends not to know Jin-il, and Jin-il escapes custody. Hyung-suk then warns his henchman that Ga-young will be released only if she proves too troublesome to keep around.
As the net tightens, Jin-il shadows Hyung-suk and discovers that he has a daughter. In a desperate bid to protect Ga-young, Jin-il abducts the girl. Hyung-suk agrees to release Ga-young if he can locate her, while Sung-hoon tailors his pursuit to follow Ga-young to Jin-il. Ga-young reaches a rooftop at a train station, where Jin-il braces for an imminent crisis, and he vows to disappear for a long while as police close in. Sung-hoon arrives with his henchmen, attempting to seize Ga-young, and attacks Jin-il. With his daughter safe, Hyung-suk rushes to the roof, frees Ga-young, and clashes with Sung-hoon, before turning his ire toward Jin-il for taking his daughter. Ga-young steps in, and Sung-hoon taunts their fated reunion after prison. In a final, brutal push, Jin-il shoves Sung-hoon over the rooftop railing, carrying himself over as well. They plummet several stories, and the scene leaves their fates ambiguous as the credits roll, with Jin-il shown moving weakly, leaving open whether either man survives.
