A well-mannered person is characterized by the fact that, despite a strong desire to express aggression, they maintain self-control and show friendliness to the world. Detective Ivan Podushkin follows the same tactic, always greeting clients politely—even if they arrive unexpectedly. Doctor Rudolf Derevyankin turns to Ivan with a shocking problem: his eccentric mother, Ellie, died under strange circumstances, and the autopsy revealed that she had been poisoned with a mixture of different medicines. Rudolf asks Ivan to find the culprit. During the investigation, the detectives come across a mysterious “Great High Priest,” whose rites in the abandoned village of Bakino connect Ellie’s life, her friend Nicoletta’s life, and other influential people. Occult gatherings, a cemetery with secrets, and water from a sinister swamp become the keys to uncovering the truth about her death.