Ever since he was a young "bot", Rodney dreamed of becoming an inventor and meeting his childhood hero Bigweld. When his father's boss becomes angered by one of his inventions, Rodney decides to leave Rivet Town, to go to Robot City and sell his idea to Bigweld. He finds that Bigweld has been replaced by Ratchet, a smooth-talking but sinister robot. After being evicted from the boardroom, Rodney meets the Rusties, a group of "outmodes" (outdated bots with worn out or broken parts). The outmodes befriend Rodney after he is able to fix most of them. He extends this favor to all the broken or crumbling robots in the City. Rodney and Fender eventually discover that Ratchet is the one who stopped the production of replacement parts, in order to force all robots to receive regular upgrades. Ratchet al forced Bigweld into hiding, to keep his plan a secret. Rodney and the other robots then unite to save Bigweld and defeat Ratchet, awaken Robot City, and the outmodes finally receive their much-needed replacement parts. In the end, Bigweld names Rodney as his successor.