Pongo is a young and mischievous gorilla living in the mountains of Africa. He wants to grow up to be brave and clever like his dad, and perhaps even become leader of the pack one day. But it is not until his little sister, Whoopsie, is born that Pongo discovers that growing up isn't just about having a big chest to thump! Can he prove that he isn't as young and irresponsible as everyone thinks?