Dong Goo, a lowlife thug, has always been living a hopelessly miserable life. One day, he accidentally obtains a bankbook with a large amount of money, as much as one billion won. He travels down to Busan to try to obtain the PIN number for the bank account. As Dong Goo meets the eight-year-old boy, Bok Gi, who believes Dong Goo is his dad, and the boy’s mother, Ae Sook in Busan, their story begins.