In Rivet Town, Rodney Copperbottom is a young inventor who dreams of making the world a better place. He idolizes Bigweld, a master inventor and owner of Bigweld Industries. During Rodney’s adolescence, he invents a gadget called the Wonderbot, intended to help his father Herb clean dishes at a restaurant. When Herb’s supervisor confronts them, Wonderbot breaks the dishes, causing Herb to be put in debt and Rodney to be dismissed. Rodney takes his invention to Robot City to see Bigweld and get a job as an inventor at Bigweld Industries, so that he can help Herb pay back his supervisor. Herb encourages him and confides that he has always regretted not pursuing his dream of becoming a musician. Rodney arrives in Robot City and meets outmoded robot Fender Pinwheeler. After a spectacular, but harrowing, ride on the Crosstown Express, Rodney arrives at the gate of Bigweld Industries.
However, he learns that Phineas T. Ratchet has taken over Bigweld Industries and is about to discontinue the manufacture of spare parts. Ratchet believes the company can make a bigger profit if it focuses on selling expensive upgrades; if the robots refuse, they are sent to the underground Chop Shop, where they are shredded and melted down by the owner of the Chop Shop, Madame Gasket, who is Ratchet’s mother. Rodney is forced out and shares quarters with Fender at a low-rent boarding house owned by Aunt Fanny, occupied by a group of other outmoded robots threatened with the Chop Shop, called the “Rusties”. When news gets out that spare parts have been discontinued by Bigweld Industries, Rodney begins fixing old robots on his own. Upon discovering this, Gasket orders Ratchet to stop Rodney and destroy Bigweld.