Sang Jin, a formerly promising vocalist, now works as a high school music teacher after suffering from a vocal cord tumor. His ordinary life becomes full of drama when Jang Ho, a local teenage gangster, is transferred to Sang Jin's school. Jang Ho is a thorn in Sang Jin's side, but upon hearing Jang Ho sing, he is deeply impressed with his natural talent and decides to commit to his training. As the two develop their special bond, an unexpected conflict arises between the two gangs in town which forces Jang Ho into a critical situation. ~~ Based on the real-life story of Kim Ho Joong.