The film tells the story of Hao Shuai, who is experiencing a midlife crisis, suddenly learning that his 10-year-old son Duoduo has no blood relationship with him, so he takes Duoduo on a "Western child exchange journey" and tells Duoduo that this is a "summer growth plan". On the train, Duoduo runs away in anger after learning about his father's real plan. The young and smart Duoduo arrives in the West alone and begins to enjoy a unique "good time". Hao Shuai, who got off the wrong train, regrets it and experiences all kinds of embarrassing things along the way to find Duoduo. On the other hand, Jin Dafa, Duoduo's biological father in the western countryside, also sent people to look for him after knowing that Duoduo is lost. Although he cooperates with Hao Shuai on the surface, he actually hides his selfishness and tries his best to take both the adopted son and the biological son for himself. In the end, Hao Shuai finds Duoduo at Jin Dafa's house after thousands of trips, and they also see their respective sons; but at this moment a "Hongmen Banquet" is about to begin. Standing at the crossroads of human nature, is blood relationship or true love important? It's like a joke from God, and it's more like a gift to each other.