At a rural England garage, two children, Jeremy and Jermima Potts, find a car formerly used for racing in the European Grand Prix until it crashed in 1909. They beg their father, down-on-his-luck inventor Caractacus Potts, to get the car for them; he makes multiple unsuccessful attempts to sell his inventions in order to raise money to but it, until he earns tips from a song-and-dance act at a carnival. He purchases the car and gives it a new name, "Chitty Chitty Bang Bang" for the unusual noise of its engine. In the first trip of the car, Caractacus, the children, and a wealthy woman they've had unflattering encounters with before, Truly Scrumptious, picnic on the beach. Caractacus tells them a story about nasty Baron Bomburst, the tyrant of fictional Vulgaria, who wants to steal Chitty Chitty Bang Bang.The story begins with the quartet escaping Bomburst's pirates. The Baron sends two spies to capture the car, but they capture Lord Scrumptious, and then Grandpa Potts by chance, mistaking each for the car's inventor. Truly, and the children see their grandfather, Bungie Potts, being taken away on an airship, following it to Vulgaria, which involves the magic car sprouting wings and propellers to fly. Grandpa is taken to the castle, and is ordered by the Baron to make another floating car just for him. He bluffs his abilities to the Baron to avoid being executed. The Potts' party is helped and hidden by the local Toymaker who now works for the Baron. Chitty is discovered and taken to the castle. While Caractacus and the Toymaker search for Grandpa, and Truly searches for food, the children are kidnapped by the Baroness' Child Catcher, as children are forbidden in Vulgaria under Bomburst's rule.The Toymaker takes Caractacus and Truly to a grotto beneath the castle where the townspeople have been hiding their children. They concoct a scheme to free the children and the village from the Baron. The Toymaker sneaks them into the castle disguised as life-size dolls for the Baron's birthday. Caractacus snares the Baron, and the children swarm into the banquet hall, overcoming the palace guards and guests. In the ensuing chaos, the Baron, the Baroness, and the evil Child Catcher are captured. Chitty comes to their rescue and, at the same time, they are reunited with Grandpa. The Potts family and truly bid farewell to the Toymaker and the rest of the village, then fly back home to England.When Caractacus finishes the story, they leave the beach for home, stopping to drop off Truly at Scrumptious Manor, where Caractacus dismisses any possibility of them having a future together, with what she regards as inverted snobbery. The Potts family arrive back at the cottage where Lord Scrumptious surprises Caractacus with an offer to buy one of his inventions, the Toot Sweets, as a canine confection, renaming Woof Sweets. Realising that he will be rich, Caractacus rushes to tell Truly the news. They kiss, and Truly agrees to marry him. As they drive home, he acknowledges the importance of pragmatism as the car takes off into the air again, this time without wings.