Set in the late 80s during the height of Korea's economic crisis, three leading gangsters of the Jong No division - straight-shooter Byuk Dol, quick-tempered Gae Dduk, and street-smart Sam Bok - are roaming the streets of Seoul after spending the last fifteen years locked up in jail. Their sole mission is to find and seek revenge on Dong Pal, the very man responsible of robbing them of their precious freedom. But when they find Dong Pal, they end up taking on a reluctant job as bodyguards for Dong Pal's daughter Eun Ji and her boyfriend Myung Suk.
When high school girl Han Ye-won (Jeong Da-bin) finds an offensive note on the internet school board left by arrogant Ji Eun-seong (Song Seung-heon) from vocational school, she replies even more offensively. She doesn't know he's hot-tempered and well-known as a bully. So when Ji Eun Song starts looking for her to teach her a lesson, Han Ye Won realizes how big her mistake was...
In the spring of 1999, a group of old friends gather to celebrate their 20 year reunion. Among the group is Yeong-ho, a cold, unhappy man, whose demeanor puts a damper on the festivities. The seriousness of Yeong-ho's depression becomes apparent when he climbs a railroad bridge and looks like he might jump. At this crucial moment, memories of seven crucial episodes from Yeong-ho's past flood his mind.