Autumn 1830, in a feverish Paris still reeling from the Revolutionary Days of July, the government of Louis-Philippe, the new king of the French, tried to quell a divided but virulent opposition. The young inspector Valentin Verne is transferred from the morals department to the Security brigade, founded a few years earlier by the famous Vidocq. He must elucidate a series of strange deaths likely to destabilize the regime. Because progressing science, mixed with the esotericism then in vogue, inspires a new type of crime. Passionate about chemistry and medicine, cultivating a taste for the irrational, Valentin knows how to decipher their codes. Appointed head of the “office of occult affairs”, a special service responsible for tracking down these modern criminals, he will give proof of his extraordinary skills.