London-based gangster George Thomason (Tom Georgeson) and his right-hand man, Ken Pile (Michael Palin), a beleaguered animal lover with a bad stutter, plan a jewel heist. They bring in two Americans to help: an alluring con artist, Wanda Gershwitz (Jamie Lee Curtis) and their "weapons man" Otto West (Kevin Kline), an Anglophobe who fancies himself as an intellectual. Wanda and Otto are lovers, but hide this fact from George and Ken, pretending to be brother and sister, so Wanda can work her charms on them.
The robbery goes well, with the thieves getting away with a large sum in diamonds. The only problem is that they are briefly spotted during their getaway by an old lady walking her dogs. The group then hide the loot in a safe in an old warehouse. Soon after, Wanda and Otto betray George to the police and he is arrested. They return to collect the loot, only to find that George and Ken have moved it to an unknown location. Wanda, who was planning to double-cross Otto as well, decides to seduce George's unhappily married lawyer, Archie Leach (John Cleese), to find out where the diamonds are located. Otto becomes insanely jealous, and his interference, combined with incidences of bad luck, lead Wanda and Archie's liaisons to go disastrously wrong. Archie eventually calls off their attempted affair.
Meanwhile, George gives Ken the task of killing the old lady, the Crown's only eye witness. During his various attempts to kill her, the animal-loving Ken accidentally kills off her three Yorkshire Terriers one by one. This causes him grief, as well as grave bodily harm as each attempt goes wrong. However, the witness suffers a fatal heart attack when her last Terrier is killed, and Ken is ultimately successful in his mission.
Wanda and Otto want George to remain in jail, but with no witness he may get off. During the course of George's trial, Wanda gives evidence that will lead to a conviction rather than an acquittal. Archie, stunned by the unexpected turn in her evidence, flubs his cross-examination and inadvertently calls her "darling". Enraged, George starts a brawl that leads to everyone fleeing the courtroom. Archie's wife Wendy (Maria Aitken) is sitting in the observer's area, and Archie's antics confirm her suspicions of his affair (though it has never been consummated). After George is taken into custody, she confronts Archie and states that she plans to divorce him. With his career ruined and his marriage about to end, Archie resolves to cut his losses, find the loot, and flee with Wanda to South America. Promised less jail time, George tells Archie that Ken knows the location of the diamonds. As he is leaving to question Ken, Archie picks up Wanda while she attempts to flee the courthouse. Archie tells her he knows that Ken is aware of the hiding spot, and Wanda counters by noting she has the key to the safe deposit box.
While the courtroom drama is unfolding, Otto has been trying to get Ken to reveal the location of the diamonds. He tortures Ken by eating the fish in his aquarium one-by-one, leaving the fish called Wanda until the end. In the process, Ken accidentally mentions the location of the diamonds at a hotel near Heathrow Airport. Otto is leaving just as Archie runs into the building; Otto steals Archie's car, taking Wanda with him. Ken tells Archie, as quickly as he can given his stutter, where they are going. The two give chase.
The protagonists all end up in Heathrow. Otto and Wanda recover the diamonds, but Wanda quickly double-crosses Otto and locks him in a cupboard. Otto escapes and is briefly captured by Archie, only to turn the tables. He is about to kill Archie, but Archie manages to distract Otto by pointing out that Americans are not always winners - as shown by their loss to North Vietnam in the Vietnam war. While they are arguing, Otto is run over by a steamroller driven by Ken, seeking vengeance for the live fish Otto ate. Archie joins Wanda on
A Fish Called Wanda is a 1988 heist-comedy film written by John Cleese and Charles Crichton. It was directed by Crichton and stars Cleese, Jamie Lee Curtis, Kevin Kline, and Michael Palin. The film is about a jewel heist and its aftermath. Kline won the Academy Award for Best Supporting Actor for his performance as Otto.