Upon hearing about the story of Treasure Island, Nobita dreams of discovering and exploring his own treasure island, despite the fact all of the Earth has been mapped already.

Doraemon and Nobita discover a mysterious golden ring far beneath the ice in Antarctica, leading them to uncover an ancient, ruined city.

Doraemon and his friends travel to ancient Japan where they meet Kukuru. When Kukuru tells them that his tribe has been enslaved by Gigazombie, Doraemon decides to help him.