Police Major Ivan Petrovich Cherkasov (Andrey Smolyakov), already known to viewers from previous films of the franchise, returns to the screens again with new episodes of the 9th season of the cult retro detective Mosgaz. The filmmakers again offer viewers to immerse themselves in the atmosphere of the Soviet Union, as the plot takes place in 1981. The story about the Soviet policeman Ivan Cherkasov, who is a detective of the Moscow Criminal Investigation Department, began in 2012, when he had to investigate the case of a serial killer nicknamed Mosgaz.