Imagine the world that is populated only by robots. They live, grow, make friends, have education, get jobs- just like us. And just like us, amongst the pile of ordinary individuals there is always a mind blowing inventor, who is eager to share his knowledge and creativity with the rest of the world. One of those creative individuals is a young robots called Rodney Copperbottom (Ewan McGregor). After running away from home to go to the Robot City and fulfil his dreams of being a big inventor like his idol, Bigweld (Mel Brooks). As he manages to get aboard the train and finally arrives to the Robot City, his adventures are about to begin. First, he meets Fender (Robin Williams), a local crook who is more than eager to show him around the city. Also, Rodney manages to encounter a female robot called Cappy (Halle Berry), who is one of the executives in the company owned by his idol. As the time goes by, he never seems to be able to get hold of his idol and talk to him about some of the ideas he has. It turns out that Bigweld is being deceived into never getting out of his lab again, and no one has seen him out in years. And Rodney is more than determined to get to meet Bigweld.