Wiplala is a 4-inch-tall adolescent of about fourteen years. By coincidence, nine-year-old Johannes finds the little boy in the kitchen behind a jar of peanut butter. Johannes is happy to have something for himself, but does not manage to keep this little man hidden from the rest of the family for long. His sister, Nella Della, thinks Wiplala is an interesting boy, but father Blom does not believe in gnomes and certainly not in Wiplala, until Wiplala accidentally tinkers with the whole family when they visit a restaurant. He is unable to make them big again, and an exciting adventure of small people begins throughout the big city of Amsterdam. Will they manage to get to their home safely and will Wiplala eventually be able to make them big again? During the trip, the understanding and bond between the family members grows and everyone gains self-confidence. Now that he is small himself, Mr. Blom discovers more about his children. They turn out to be more capable than he ever thought.