The new logic teacher cancels all coursework and tests. He invites students to play an exciting game... The rules are as follows: under mysterious circumstances, an unknown maniac kidnapped the girl Polly. It is necessary to identify the criminal and save the victim before the end of the semester - otherwise Polly will die. The students are delighted! Divided into groups, they begin the investigation. But three of them - Mary, Brian and Dennis - are haunted by the thought: what if they are investigating a real crime? What if the teacher’s task is just a sophisticated game of an experienced killer? And what will happen to the victim if “amateur detectives” are like that? and they won’t catch the criminal?!