A real know-it-all always knows best. Tina and Theo Theufel are stuck with parents who don’t have a dog but constantly want to eat beets. Moreover, they always think they know better. Well, the parents do. The kids do too. After all, the apple doesn’t fall far from the tree. But at least Theo and Tina admit that they are know-it-alls. Mom and Dad deny it. This is, of course, absolutely ridiculous. Recently, the Theufels moved into an old house with an attic full of adventures. Although playing in the attic is not encouraged, Tina and Theo love nothing more than that. Additionally, the kids make a strange discovery in the attic: in a box of books lives a little creature with a big mouth. A genuine know-it-all that claims to be visible only to its kind. And one thing is for sure: being a true know-it-all is hard work. You have to be knowledgeable, quick on your feet, and relentlessly committed to correctness. Can Mom and Dad see the know-it-all too? A read-aloud book for all know-it-alls and smart alecks, regardless of age, with brilliant illustrations by Astrid Henn.