Mole's (Steve Coogan) underground home is knocked in when the field is bulldozed by Weasels; the field is owned by Mr. Toad (Terry Jones), who has sold it to raise money to finance his latest hobby: motor-cars. Mole flees to the river and meets Rat (Eric Idle), who is getting ready to embark on a picnic. Seeing Mole's distress, Rat decides to take Mole to see Mr. Toad. Toad, completely engrossed with motor cars, is not responsive to their appeals, but instead falls further into the lures of the Weasels. There are four main weasel characters in the film. Their leader is the villainous Chief Weasel (Antony Sher), who is always accompanied by three main henchman- Clarence (Keith-Lee Castle) and Geoffrey (Richard James), who both passionately hate each other, and St.John (Robert Bathurst), whose attempts at sycophancy always go disastrously wrong. The Weasels are planning to take over Toad Hall, but the full extent of their plan is unknown.
During a wild drive into the Dark Forest, which results in one more car being destroyed, all three protagonists are lost in the Wild Wood. Mole encounters the weasels, who attempt to coerce him into stopping his friends from interfering with their plans. St John almost reveals the Weasel's secret plan (which involves complete subjugation of the local area). They later encounter Toad, after fleeing when Rat arrives. All three protagonists end up in Mr. Badger's (Nicol Williamson) underground abode. Badger, a close friend of Toad's late father and feeling responsible for Toad's reckless conduct regarding his inheritance, is awakened from his deep sleep. As soon as he learns the news, Badger takes the initiative to put some sense back in Toad's head.
However, Toad refuses to listen to Badger and continues his reckless behavior which ultimately ends up with him being arrested for stealing and crashing a new motor-car. During his trial, Toad's defense lawyer (John Cleese) proves to be more of a problem than the prosecution. Furthermore, the Weasels have blackmailed the jury into finding Toad guilty. The judge (Stephen Fry) initially sentences Toad to twenty years in prison, but after Toad insults the Court and makes a botched escape attempt, the judge increases the sentence to one-hundred years. With the help of a sympathetic tea lady (Victoria Wood), Toad manages to escape from jail but only to get caught again by the Weasels, who in the meanwhile have taken over Toad Hall. They are planning to blow it up, and have built a dog-food factory over the remains of Mole's house (They also plan to construct a slaughterhouse over the remains of Toad hall). Meanwhile, their activities have damaged Badger's home, which provokes him into taking decisive action against them. Badger and Rat attempt to break into Toad Hall, but are caught by the weasels. Along with Toad, they are placed in the factory's mincing machine under the orders of the Chief Weasel. When he is gone, however, Mole (who has broken into the factory) disables the machine, enabling them to escape.
Film poster as released in the USA by Walt Disney Home Entertainment
Lulled by a premature sense of victory, the Weasels become less watchful and their leaders start quarreling among themselves for leadership, allowing the protagonists to stage a raid on the house. All the weasels are incapacitated in the ensuing fight, save the Chief who escapes. Toad attempts to stop him reaching the factory, containing the detonator necessary to blow up Toad Hall, to no avail. Unbeknownst to both of them, the explosives are actually in the factory (Rat had switched the labels on the explosive's containers earlier in the film, leading the weasels to believe the explosives are actually meat supplies for the factory), and as such the Chief blows up himself along with the factory. Afterwards, Toad makes a public speech swearing off motor cars and promising to be wiser and less prideful in the future. However, moments later, Toad flies off in an airplane he has purchased, suggesting he hasn't changed a bit after all. The film ends with Toad flying out across the country, and eventually over the sea.