Egor has another rap battle coming up. This time, Nastya alone is not enough — it's time to seek help from a higher-ranking specialist. The whole school knows that Maria Pavlovna has no equal in diss: she wrote them even before she found out about the existence of such a word. While her mother is busy verbally humiliating her, Natalia is trying to figure out which stain is more terrible for her — on her clothes or on her reputation.

Another terrible discovery strikes the head teacher of educational work: Natalia notices a louse in the student's hair. Panic reigns in the staff room. The director asks not to tell parents about what is happening and forces the team to think of a more secretive way to get rid of pediculosis. But the smell of kerosene and childhood injuries is much more difficult to eradicate than arthropod pests.