The third volume of the Collected Works includes the final novel of the trilogy, “The Albigensian Mysteries,” a story that leads the reader to the secrets of the Albigensian treasures.

Inspector Lyusin will have to investigate the circumstances of another complicated crime. Under mysterious circumstances, chemist professor Solitov disappears from his dacha. In the course of solving the crime, it turns out that Solitov was interested in ancient chemical recipes. The scientist’s scientific activity turns out to be connected with the intricate history of the alchemists’ search for the “elixir of immortality.”