Irregular Seasoning  is very freely inspired by the life of the marchioness of Brinvilliers ( 1630-1676 ). Wanting to end her days by poisoning herself with the rat poisoning, the marchioness decides to test this on one of her handmaids. She confides then a passion for poisoning, which she envisages as an art. She kills alternately her husband, her daughter and people from her circle of acquaintances, so achieving the work of her life before finishing on the stake.