Charlie and the Chocolate Factory by Roald Dahl

Eleven-year-old Charlie Bucket lives in poverty with his parents and grandparents in a town that is home to a world-famous chocolate factory. One day, Charlie's bedridden Grandpa Joe tells him about Willy Wonka, the factory's eccentric owner, and all of his fantastical candies. Rival chocolatiers sent in spies to steal his recipes, forcing Wonka to close the factory and disappear. He reopened years later, but the gates remain locked, and nobody knows who is providing the factory with its workforce.

The next day, the newspaper announces that Wonka has hidden five Golden Tickets in Wonka Bars; the finders of these tickets will be invited to come and tour the factory. The first four tickets are found by gluttonous Augustus Gloop, spoiled Veruca Salt, gum-chewing Violet Beauregarde, and television addict Mike Teavee. One day, Charlie buys a Wonka Bar with some money he found in the snow; the bar contains the fifth and final ticket. Upon hearing the news, Grandpa Joe regains his mobility and volunteers to accompany Charlie to the factory.