Zagadka Lunnogo rayona

Menya zovut Ida Ha, i ya lyublyu zagadki. Mne nuzhno stat' nastoyashchim detektivom, chtoby rasputat' eto slozhnoe delo! Nechto strannoe proiskhodit v rayone Koyo! Kto-to pytaetsya rassorit' shkol'nikov, ostavlyaya na partah i v shkafchikah tainstvennye nadpisi. Ucheniki teryayutsya v dogadkah: kto by eto mog byt'? Na pomoshch' rebyatam prihodyat Ida i Hanse. No, kazhetsya, huligan razoshyolsya ...