A well-known psychologist Anzhej Kowalski lives is a gorgeous mansion in suburban village. He collects ancient keys all around the world. Dr. Kowalski practices an original method: after listening to his patient he chooses a special key from his collection. The patient gets inspired by this gift - and finds a way out of his difficult situation. But this time Dr. Kowalski gets into trouble: his housekeeper Anatoly has disappeared without a trace. The psychologist hires detectives Ilyushin and Babkin, who arrive to the mansion along with other patients and start secret investigation. There are so many strange details in this case. Anzhej obviously disliked his housekeeper, he did not go to police after he disappeared, and he clearly did not tell everything to the detectives. And doctor's guests are also suspicious, each in his own way. Ilyushin believes that there is a dangerous lunatic among the guests: a member of the Gatekeeper sect .
