Amateur sleuth Flavia de Luce, along with her pestilent younger cousin, investigates the murder of a former public hangman and uncovers a secret that brings the greatest shock of her life. Flavia de Luce has taken on the mentorship of her odious moon-faced cousin Undine, who has come to live at Buckshaw following the death of her mother. Undine&rsquo,s main talent, aside from cultivating disgusting habits, seems to be raising Flavia&rsquo,s hackles, although in her best moments she shows potential for trespassing, trickery, and other assorted mayhem. When Major Greyleigh, a local recluse and former hangman, is found dead after a breakfast of poisonous mushrooms, suspicion falls on the de Luce family&rsquo,s longtime cook, Mrs. Mullet. After all, wasn&rsquo,t it she who&rsquo,d picked the mushrooms, cooked the omelet, and served it to Greyleigh moments before his death? &ldquo,I have to admit,&rdquo, says Flavia, an expert in the chemical nature of poisons, &ldquo,that I&rsquo,d been praying to God for a jolly good old-fashioned mushroom poisoning. Not that I wanted anyone to die, but why give a girl a gift such as mine without giving her the opportunity to use it?&rdquo, But Flavia knows the beloved Mrs. Mullet is innocent. Together with Dogger, estate gardener and partner-in-crime, and the obnoxious Undine, Flavia sets out to find the real killer and clear Mrs. Mullet&rsquo,s good name. Little does she know that following the case&rsquo,s twists and turns will lead her to a most surprising discovery&mdash,one with the power to upend her entire life.