The small southern town of Onsung in 2005. Tae-soo, a detective from Seoul, returns to his home town for the first time in almost a decade to attend the funeral of his friend, Wang-Jae. At the funeral Tae-soo becomes reacquainted with his close friends from his teenage years, Pil-ho, Suk-hwan, and Dong-hwan. Learning that Wang-jae’s death was allegedly the result of a quarrel with hoodlums, Tae-soo extends his visit and starts to look into the circumstances of the homicide himself.

Searching for clues in a now unfamiliar town, Tae-soo receives a rough welcome from the town’s hooligans. During a confrontation between Tae-soo and some local gangs, reckless Suk-hwan shows up to save Tae-soo. Following the incident, Suk-hwan and Tae-soo form a close bond and seek to avenge the death Wang-jae. But as they begin to follow up more clues, several of the whistleblowers they have taken into custody, as well as some of the town’s locals, meet untimely ends. Tae-soo and Suk-hwan declare war on the unidentified enemies, with each covering the other’s back. It’s not long before Tae-soo and Suk-hwan discover the truth surrounding the deaths of several innocent people, including their friend.