Sixty-year-old self-educated working-class Kempton Bunton appears in Court Number 1 at the Old Bailey, pleading not guilty to charges of stealing Goya's Portrait of the Duke of Wellington and its frame from the National Gallery in London.

Kempton himself is sacked from his job as a taxi driver due to being over-talkative to passengers and giving a free ride to an impoverished disabled First World War veteran.

An unseen man with a north-east English accent steals the painting, and after Kempton's return to Newcastle, he and Jackie make a false back to a wardrobe to hide it.

Kenny and his married-but-separated lover Pammy come to visit his parents and she spots the painting in the wardrobe, revealing this to Kempton in hopes of getting half the £5,000 reward offered.

Panicked, Kempton abandons a suggested Daily Mirror plan to raise money for his campaign via an exhibition of the painting and instead walks into the National Gallery to return it and confess to the theft.

Their reconciliation is evident when they are sitting together in a cinema watching the James Bond film Dr. No, and chuckle when they see the scene that shows Sean Connery spotting the "stolen" Goya painting of the Duke of Wellington.

Four years later, Jackie admits his guilt to the police, but they and the Director of Public Prosecutions fear that a new trial could lead to Kempton being called as a witness and again becoming an embarrassing cause célèbre.

Text at the end of the film states the frame was never recovered and that no plays by Bunton were ever produced, but that, in 2000, TV licences were made free to those over age 75.

The website's critical consensus reads, "A sweet swan song for director Roger Michell, The Duke offers a well-acted and engaging dramatization of an entertainingly improbable true story.