The film is a comedy about a jewel heist and its aftermath. The heist is planned by George Thomason (played by Tom Georgeson) whose right-hand man is Ken Pile (Michael Palin), an animal lover with a bad stutter. They bring in two Americans: an alluring con artist, Wanda Gershwitz (Jamie Lee Curtis) and a "weapons man", Otto West (Kevin Kline). Wanda and Otto are lovers pretending to be siblings so that Wanda can work her charms on George and Ken.
After the robbery, Wanda and Otto betray George to the police but discover that George and Ken have moved the loot to a new location. Wanda decides to seduce George's lawyer, Archie Leach (John Cleese), to find out where it is. Meanwhile, Ken is charged by George to silence a key witness.
There is subsequent confusion and slapstick. For example, with Ken accidentally killing the witness' three Yorkshire Terriers one by one, instead of the witness. The witness eventually suffers a fatal heart attack when her third Terrier is killed by accident. The title is derived from the name of Ken's tropical fish which Otto threatens to eat alive during the farcical torture scene.
Archie and Wanda gradually fall in love and the movie ends with those two leaving the country and Ken finally having his revenge on Otto by running him over with a steamroller.
The film was an enormous critical and commercial success when it was released and has remained a popular favorite since. Kline received wide acclaim and won an Academy Award for Best Supporting Actor for his work. Cleese and Crichton received an Academy Award nomination for Best Original Screenplay.
In 2000, the readers of Total Film magazine voted A Fish Called Wanda the 37th greatest comedy film of all time. In 2004 the same magazine named it the 41st greatest British film of all time. In 2000, the American Film Institute ranked the film 21st on its list of the 100 funniest movies ever made. This film is number 27 on Bravo's "100 Funniest Movies". It is also included in the Reader's Digest list of the "100 Funniest Films" (a list rather than a ranking). A Fish Called Wanda was one of only 24 movies to be named on all three of the A.F.I., Bravo and Readers' Digest "top 100 funniest" lists. The movie also garnered an impressive and rare 100% rating on Rotten Tomatoes.
In 1989, a Danish audiologist, Ole Bentzen, died after laughing while watching the film. His heart was estimated to have beat at between 250 and 500 beats per minute, before he succumbed to cardiac arrest.
John Cleese and his daughter, Cynthia (who played Portia), have reportedly started to work on a stage musical version of the film.