In the village of Momchilovo, located at the very foot of Karabair, someone has broken into a military facility and stolen some secret blueprints and money, assaulting a gate guard in the processes. Both the day before and the night of the crime, short-wave radio broadcasts were detected near there. The prime suspect is a young male teacher and he is certain to take the fall for it except counter-espionage agent Avakum Zakhov has his doubts.