It all starts when a travelling circus arrives in a small village... Everyone is intrigued and excited to see the show, which is said to feature a terrifying monster. That evening, Otto, the narrator, takes a seat in the tent. But when the curtains open, the reader gets a big surprise: the monster on the stage is actually a human child, while the audience is full of terrifying, grotesque monsters! Otto, whose face is finally revealed, is also a hairy monster. Little by little, Otto and the human child get to know each other, and change the way they both look at the world.