JANG Ga-pil, a typical businessman in his forties, comes home one day to discover that his daughter has been sexually assaulted by a group of schoolboys, among them the school’s boxing champion, KANG Tae-wook. Lacking the resources and influence to seek justice, he decides to confront KANG with a knife on his way to school. However, this attempt goes awry. In an unexpected turn, another student, GO Seung-suk, offers to train Ga-pil in combat over the course of 45 days.