Lee Jieun runs away from home after finding out a huge secret. She isn't her father's child. Her mother had an affair with someone while her workaholic father was away for a business trip. Now that her dad has found out this secret, he leaves Jieun alone with her drunkard of a mother. As she runs away, she's caught. And now she's accepted to live with an ex-gangster and his ex-gang. Little did she know that they were once the most dangerous group in Korea. What will happen to Jieun now? Is Yoseob, the ex-gangster, really as trustworthy as he makes himself seem?