The main plot of the film is that the mice leaving New York will help in the building and of a new town, where mice and cat can co-exist. The "dreamer" who convinced them is Cat R. Waul, an ambitious businessman with a ruthless streak. He sees the mice as cheap labor. Once they have build HIS town and outlived their usefulness, Cat intents to kill them.Leaving him free to run the place and its industry.
Fievel is a fascinated with the dime-novel version of the West. But will have to receive some lessons from his hero Wylie Burp (loosely based on Wyatt Earp), who is now old and tired. Meanwhile, teenaged Tanya Mousekewitz attempts to launch a career as a saloon singer. And Cat finds himself genuinely fascinated with the girl and her voice.