Fievel gets separated from his family and is swept away in a bottle which goes to London, England. Then he meets Dr. Dawson and reunites with Basil and Nellie, and also his best friend, Tiger, and he (Tiger) and Fievel need their help for them to get back and be with his family again. Fievel also meets a girl mouse named Olivia which Basil knows and he (Fievel) seems to have a crush on her and Fievel and Olivia fall in love. Fievel also greets her father Hiram Flaversham. Then he meets an evil mastermind and Basil's arch enemy, Ratigan The Napoleon of Crime who hates being called a rat. Fievel must rescue his feline friend from getting into trouble and stop Ratigan from kidnapping his new friend Olivia and killing them before Ratigan finishes his evil dirty deed.
