Young Charlie Bucket lives in poverty in a tiny broken down house with his parents and four grandparents, Grandpa Joe, Grandma Josephine, Grandma George, and Grandma Georgina. His grandparents share the only bed in the house, located in the only bedroom. Charlie and his parents sleep on a mattress on the floor. One day, Grandpa Joe tells him about the legendary and eccentric chocolatier, Willy Wonka and all the wonderful candy he made until other jealous candymakers like Bill Fickelgruber, Prodnose, and Arthur Slugworth sent in spies to steal his secret recipes, which led him to close the factory forever. The next day, the newspaper announces that Mr Wonka is reopening the factory and has invited five children to come on a tour, after they find a golden ticket in a Wonka Bar. Each ticket find is a media sensation and each finder becomes a celebrity. The first four golden tickets are found by the gluttonous Augustus Gloop, the spoiled and petulant Veruca Salt, the gum-addicted Violet Beauregarde, and the TV-obsessed Mike Teavee.
One day, Charlie sees a fifty-pence coin (dollar bill in the US version) buried in the snow. He then buys himself a Wonka Bar and finds the fifth golden ticket and shows it to his parents. The ticket says he can bring any family members with him to the factory and Charlie's parents decide to allow Grandpa Joe to go with him.
After meeting Mr Wonka, the kids and their parents go inside where they meet Oompa-Loompas, a race of small people who help Mr Wonka operate the factory since he rescued them from poverty and fear in their home country Loompaland. The other kids are ejected from the factory in comical, mysterious and painful ways. Augustus gets sucked up the pipe after falling into the Chocolate River in the Chocolate Room, Violet blows up into a giant blueberry after sampling an experimental three-course chewing gum meal in the Inventing Room, Veruca is thrown down the garbage chute in the Nut Room after the nut-testing squirrels consider her a "bad nut," and Mike gets shrunk after he tries to be the first person to be sent by television in the Television Room's Television Chocolate Technology. With only Charlie remaining, Mr Wonka congratulates him for "winning" the factory and, after explaining his true age and the reason behind his golden tickets, names Charlie his successor. They ride the Great Glass Elevator to Charlie's house while the other four children go home (Augustus squeezed thin, Violet all blue in the face, Veruca covered in garbage, and Mike stretched ten feet tall). Afterwards, Mr Wonka invites Charlie's family to come live with him in the factory, and they do.