In the old English estate of Bookshaw, the last representatives of the aristocratic family live - the eccentric Colonel de Luce and his three daughters. In the summer of 1950, the swamp of rural life disrupts incredible events: the murder of a stranger and the arrest of a colonel. While older daughters, as expected by a well-bred English lady, weep in handkerchiefs, the youngest, eleven-year-old Flavia, is delighted: Finally, something happened in her life! An analytical mindset, a passion for chemistry and especially for poisons will help her understand this puzzle case, which broke the teeth of local police . Flavia embarks on a quest that will lead her no more or no less than to the King of England in her own person. One thing she is sure: the father is innocent on the contrary, he protects his daughters from something terrible.