The 7 brothers of the forge

When, in 1822, Brother Copper, with the benevolence of Élie de Montgolfier, owner of the Fontenay Abbey, installed in the old forge the lay community that everyone called The 7 Brothers of the Forge, he did not expect such a deluge of violence; yet his only ambition was to maintain the tradition of copyist-illuminators and the safeguarding of a fabulous collection of original manuscripts.
 Following the theft of the only book of The Most Holy Trinosophy written in the 18th century by the famous Count of Saint-Germain, a morbid suspicion invades the minds of both members of the community and those in the Fontenay region.
 Then terror sets in when the first murder of a brother is discovered!
 And why doesn't Brother Copper want to notify the police?
 When a new brother is murdered, there is no doubt: someone informed of the existence of a secret protected by the community is trying to seize it.
 What is the nature of this secret? Nicolas Flamel, the famous 14th-century alchemist, and a certain Abraham the Jew are mentioned. What do they have to do with these 19th-century murders?