About the events of the final stage of the Second World War — the defeat by Soviet and Mongolian troops of the selected Kwantung army. Bacteriological weapons were created in the laboratory of Japanese General Ishii Shiro. Experiments were conducted on prisoners of war and political prisoners. Epidemiologist Dmitry Sokolov was assigned to solve the mystery of this laboratory. At the cost of his own life, he completed the task. The march of Soviet and Mongolian formations through the Gobi sands and the Khingan spurs was not only a brilliant military operation, but also a warning of the use of bacteriological weapons by Japan.