Paris, 1797. When illiterate servant girl Jeannette Moineau is accused of poisoning her master, police investigator Aristide Ravel cannot believe she is guilty. With stubborn witnesses, a mysterious white powder, and stolen goods all stacked against her, however, he knows it will not be easy to clear her of the charges. But he finds an unexpected ally in Laurence, a young widow of the house, whose past surprisingly intersects with his own.In a large household overcome with bickering and resentment, everyone seems to have a motive for poisoning old Martin Dupont. Ravel and Laurence probe the secrets of the city's crafty politicians and confidence artists for clues, but as more family members turn up dead, the list of suspects rapidly dwindles...