When Milo Ames receives a troubling letter from his childhood nanny, Madame Nanette, he and Amory travel to Paris where they are soon embroiled in a mystery surrounding the death of a famous parfumier. Helios Belanger died suddenly, shortly before the release of his newest, highly-anticipated perfume, and Madame Nanette, who works for the family, is convinced that her employer’s death was not due to natural causes.