Unable to bear the summer heat, Doraemon transports Nobita and his friends to a huge iceberg floating in the South Pacific. While creating an amusement park with the secret tool "Ice Working Iron", the group finds a mysterious golden ring in the ice. Upon further examination, he determines that the ring was buried in Antarctica 100,000 years ago, before people could have lived there. Doraemon and his friends go to Antarctica in search of the owner of the ring and find the ruins of a great city buried in the ice. Using Doraemon's time belt, the group travels back 100,000 years and meets the young Kara, who is connected to the mysterious ring. But now the group must fight to survive while Doraemon faces the crisis of the freezing of the entire Earth.