Lee Jang Suk has not had the easiest life. Starting from a young age, he has been picking pockets of unsuspecting strangers to get by. After being caught, Jang Suk spends time in juvenile hall. When he is released, he is at risk of falling back to his old ways but dreams of becoming a K-1 fighter, a form of kickboxing competition. When he meets Nam Jae Yul, a washed-up sports agent, they both see a chance to get their lives back – with the help of Tae Bo instructor Park So Yeon.