The plan was simple, and just as easily it failed... Climbing into the teachers' room on a dark night, Genka Karmashkin missed the magazine of the 8th "B"! He only needed a minute - how much time does it take to put a couple of fours next to his last name? Genka was interrupted by an unknown person in a mask: he managed to steal the magazine first! And now the boy is in big trouble - the head teacher found his keys to the school and threatens him with expulsion if the missing keys are not returned in two days. So, Genka should conduct his own investigation? And his suspects include the whole class?!