Paris XVIII century.
A young man named d'Eon de Beaumont is happy that he will soon meet his elder sister Leah, whom he has not seen for many years. Lia de Beaumont now lives in the court of Louis XV. However, the feeling of joy quickly passes due to a terrible accident: the entire crew, who accompanied the noble lady and was close to the royal family, was brutally murdered. Leah herself was missing. The only evidence at the crime scene: The word "PSALMY", written in the blood of the victims ...
D'Eon insists on his participation in the investigation and finds out that four more young girls have also disappeared under strange circumstances.
The situation becomes more mysterious after the disappearance of the evidence and after the young man, for no reason, is removed from the investigation. But d'Eon is driven by a secret force that forces him to continue the investigation. The knight is immersed in the mystical game of duplicity, which will lead him directly to the Secret of the King and the secret police of His Majesty, where he began to serve in the hope of finding his sister ...
