In October 1979, a terrible explosion occurred at a railway station: the wagons carrying an explosive substance slipped off the brake chocks and collided with a passing freight train. While doctors from “Emergency Help” were treating the victims, they accidentally discovered a green notebook containing encrypted notes. These could lead to the trail of a successfully operating large criminal group—though it won’t be easy, because on the other side there is an excellent chess player who can calculate every move and doesn’t shy away from the harshest tactics.