Rodney Copperbottom is a talented inventor who hopes to make his fortune by moving to Robot City and working among the nuts and bolts of the robotics industry. Rodney fantasizes about building robots for his boyhood hero and master inventor Big Weld, but when he meets him, Rodney’s dream threatens to turn rusty. Big Weld reveals that his company is now being run by the evil Phineas T. Ratchet, a merciless moneymaker who wants to rid the world of the antiquated robots that clutter up the streets of Robot City. This leaves Rodney’s aspirations needing a major oil change, and with little chance of finding work, he feels about as useful as a broken spare part. So he takes to the streets, where he finds some unlikely salvation in a group of robots lead by Fender. Fender urges Rodney to help save them from the scrap heap, while Ratchet and his company create threatening new policies on robot reconstruction. The ensuing action leads to a breathtaking set of adventures in the futuristic city.