Dong-goo, a lowlife thug, has always been living a hopeless miserable life. One day, he accidentally obtains a bankbook with such a large amount of money as much as one billion won. He travels down to Busan in order to try to obtain the PIN number for the bank account. As Dong-goo meets the eight year old boy, Bok-gi (Jo Won-bin), who believes Dong-goo is his dad, and the boy’s mother, Ae-sook (Hong Ah-reum) in Busan, their story begins.
八公（Forest 饰）是一条谜一样的犬，因为没有人知道它从哪里来。教授帕克（理查·基尔 Richard Gere 饰）在小镇的火车站拣到一只走失的小狗，冥冥中似乎注定小狗和帕克教授有着某种缘分，帕克一抱起这只小狗就再也放不下来，最终，帕克对小狗八公的疼爱感化了起初极力反对养狗的妻子卡特（琼·艾伦 Joan Allen 饰）。八公在帕克的呵护下慢慢长大，帕克上班时八公会一直把他送到车站，下班时八公也会早早便爬在车站等候，八公的忠诚让小镇的人家对它更加疼爱。有一天，八公在帕克要上班时表现异常，居然玩起了以往
