In October 1979, a terrible explosion occurred at the railway station - cars in which an explosive substance was transported fell off their brake shoes and collided with a passing freight train. While providing assistance to the victims, the ambulance doctors accidentally discovered a green notebook containing encrypted notes. They can get on the trail of a successful large criminal group, but this will not be easy, because on the opposite side there is an excellent chess player who knows how to calculate all the moves and does not shy away from the toughest techniques.