Vĩnh is a seventh-grade student whose disruptive nature and disregard for studying has greatly frustrated his parents and the school staff alike. When all the teachers end up refusing to take Vĩnh in out of fear of having to deal with his notorious tantrums, only a young teacher, Mrs. Hồng Vân, welcomes the boy into her class with open arms.

A schoolboy dreaming of building a giant crane and a sturdy dam finds himself inspired by the legend of The Mountain God and The Lord of the Waters. His reimagination sets it up for the future, where science and technology will enable a post-war Vietnam to conquer nature and move forward.