Dong-gu, a third-rate punk who makes a living from job placement center work, is constantly threatened by gangsters for failing to pay his debts. One day, Dong-gu witnesses Ki-cheol, a gangster, being attacked by his associates. Dong-gu discovers a bankbook containing 1 billion won that Ki-cheol was hiding! Seizing a once-in-a-lifetime opportunity to change his chaotic life, Dong-gu heads to the countryside to find Ae-sook, who knows the bankbook's password. However, Ae-sook, Dong-gu's first love, is in a coma, and beside her, he meets Bok-gi, a 10-year-old boy, and his grandmother, Geum-soon. Bok-gi, who has been waiting for a father he's never met, welcomes Dong-gu joyfully, and to find the bankbook's password, Dong-gu begins living with Bok-gi by pretending to be his father. Meanwhile, the gangsters are hot on the trail of the bankbook...