A messenger between Doctor Haas and Western Germany scout group gets killed at an airport of one of the European countries. A cipher for purchasing raw materials for mass production of RH gas is found in his pocket. It is necessary to clarify the following: in one of the Western resort towns a German war criminal Dr. Haas is finalizing his work over a new psycho-chemical weapon – RH gas under the guise of a pharmaceutical center. The gas works in the following way – in small doses it stimulates a human intellectual potential, in large ones it turns him into a joyful idiot and a robot workaholic. A Soviet scout colonel Konstantin Timofeevich Ladeynikov takes the case of Dr. Haas. The main difficulty is that Ladeynikov got to the field of view of special services, but the scout asks permission from his superiors to stay in the country and continue his work. But Ladeynikov does n’t have Haas’ portrait. He needs a person who can identify him. Head of KGB applies to an actor of a children's theater, a father of two children, Ivan Pavlovich Savushkin requesting him to create Haas’ portrait. In 1944 Savushkin escaped from a Nazi concentration camp, where Haas conducted his deadly experiments, turning people into animals with no life sense. After some time, Savushkin understands how much depends on him in the Haas operation and agrees to help Ladeynikov. Besides, he knows German very well.