This is a story about robots. The rank of a robot depends on the material it is made of. Rodney, who is made of copper, is the humblest robot. But Rodney is not born with low self-esteem. He believes that he has the brain of an inventor. Although life in the small town is peaceful, it cannot satisfy Rodney's ambition. He decides to go to the "Robot City" to visit the famous inventor "Big Weld". So on this day, Rodney set off with his proud invention. However, the prosperous "Robot City" confuses Rodney, who came from the countryside. Fortunately, a group of robots called "scrap copper and rotten iron" reached out to him, allowing Rodney to temporarily settle down in the city. At the same time, a group of saboteurs are planning to destroy the "Robot City"...