The Great Mouse Detective (released as Basil the Great Mouse Detective in some countries and The Adventures of the Great Mouse Detective during its 1992 re-release) is a 1986 American animated mystery adventure film produced by Walt Disney Feature Animation and released by Walt Disney Pictures. Based on the children's book series Basil of Baker Street by Eve Titus and Paul Galdone, the film is written and directed by John Musker, Dave Michener, Ron Clements, and Burny Mattinson in their feature directorial debuts. Featuring the voices of Vincent Price, Barrie Ingham, Val Bettin, Susanne Pollatschek, Candy Candido, Diana Chesney, Eve Brenner, and Alan Young, the plot follows a mouse detective who undertakes to help a young mouse find and save her father from the criminal mastermind Professor Ratigan.

Plot

In 1897 London, a young mouse named Olivia Flaversham celebrates her birthday with her single father, toymaker Mr. Flaversham. However, a bat with a crippled wing and a peg leg arrives unexpectedly and kidnaps Flaversham. Olivia leaves to find Basil of Baker Street, the famous Great Mouse Detective, but gets lost. David Q. Dawson, a retired army surgeon mouse newly returned from Afghanistan, meets Olivia and escorts her to Basil's residence. Being busy already, Basil initially dismisses them. Olivia then mentions the bat that abducted her father, and Basil realizes that Olivia saw Fidget, the assistant of Professor Ratigan, the criminal mastermind whom Basil was working to catch. It is then revealed that Ratigan kidnapped Flaversham to create a clockwork robot replica of the Queen of the Mice, so that Ratigan can usurp her place as "Supreme Ruler of all Mousedom". Flaversham initially refuses to participate in the scheme, but capitulates when Ratigan threatens to harm Olivia.