The Affair of the Poisons proper opens in February 1677 after the arrest of Magdelaine de La Grange on charges of forgery and murder.

She appeals to François-Michel le Tellier, Marquis de Louvois, claiming that she has information about other crimes of high importance.

Louvois reports to the King, who tells Gabriel Nicolas de la Reynie, who, among other things, is the chief of the Paris police, to root out the poisoners.

La Reynie seeks to calm the King.

The subsequent investigation of potential poisoners leads to accusations of witchcraft, murder and more.

Authorities rounds up a number of fortune tellers and alchemists that are suspected of selling not only divinations, séances and aphrodisiacs, but also "inheritance powders" (aka: poison).

Some of them confess under torture and give the authorities lists of their clients, who had allegedly bought poison to either get rid of their husbands or rivals in the court.