Come out and play with me. A tale

No one likes the always collected and neat class president of the seventh "D", Nastya Sovyetnikova. After all, she constantly scolds her classmates for some minor faults and even writes down all their misdeeds in a special notebook.
But one day, everything changes. Nastya no longer pays attention to her classmates, walks around the school looking around, and is also afraid of phone calls. She destroys her completed homework, crows and caws instead of answering… What happened to the perfect straight-A student? What secret is she hiding? Only the class detective, Clarissa Mironoff, can handle this many mysteries…