The year is 1951. At a crumbling manor house outside a picturesque British village, where the de Luce family has resided for 500 years, a dead body lies in the cucumber patch. Flavia de Luce, a brilliant eleven-year-old chemist whose specialty is poisons, stumbles upon the body in the middle of the night and discovers her true calling: sleuth. Flavia is determined to figure out how the dead body got that way. But when her father Havilland confesses to the murder, she must turn every trick in the detective manual to save him, keeping two steps ahead of the local constabulary, and one step ahead of the actual murderer, who now has an eye on her. Little does Flavia know that her intrepid investigating to free her remote, enigmatic father will unveil his deepest secrets, and lead to truths about her deceased mother Harriet, a spy, in whose footsteps Flavia is destined to follow.