Fievel Goes to London is an upcoming British-American animated adventure crossover movie with the An American Tail films and 1986's The Great Mouse Detective. This will be released by Universal Pictures and Walt Disney Pictures.
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.
- Fievel Mousekewitz - (The main protagonist, voiced by Thomas Dekker) A courageous and outgoing young mouse who is fashioned to be a hero and is trying to find his family.
- Tiger - (The secondary protagonist, voiced by Jim Cummings) A big fat cat who is Fievel's adoptive best friend and sidekick of the Mousekewitz family.
- Basil of Baker Street - (The deuteragonist, voiced by Barry Bostwick) A mouse detective who helps Fievel find a way back and be with his family.
- Nellie Brie - (The second deuteragonist, voiced by Emily Blunt) A female mouse reporter of The Daily Nibbler who also helps Fievel find his family and she is also Basil's girlfriend.
- Dr. David Q. Dawson - (The third deuteragonist, voiced by James McAvoy) A mouse surgeon who meets Fievel at Baker Street's Underground Station and also helps him (Fievel) find his family and is also Basil's assistant.
- Olivia Flaversham - (The tritagonist, voiced by Andrea Caron) A young girl mouse who is Hiram Flaversham's daughter is also Fievel's love interest, who coincidently tries to find her father after he gets captured once again by Ratigan, and she would bond with Fievel in search for their families later on.
- Professor Ratigan - (The main antagonist, voiced by Corey Burton) Basil's arch enemy and The Napoleon of Crime who hates being called a rat and wants to be the Royal Councillor of England, longing to take over the world.