The story begins with the introduction of the girl Sonia to the monster Mo, who looks like a sheaf of pink hay with blue specks. But monsters have never been friends with children before and are specially vaccinated against childbearing (a terrible disease among chimeras). In a few months, Mo has to earn seven thanks from people to prove that there is friendship and kindness in the human world, otherwise he will be thrown into the Land of Horrors.

And this is not easy to do, because the ghoul Very Angry Shark, on the contrary, not only makes sure that the rules of the game are followed correctly, but also hinders his friends. Mo and Sonya face a fire, a letter to the grandfather, the pursuit of Sonya’s suspicious relative Vova, who pretends to be a chemist and secretly conducts experiments with blood, and many more adventures and dangers await the heroes, but true friendship makes real miracles. It is the first book in a trilogy of books about the Marvelous Monster.