Flavia is an 11-year-old girl who lives in the English countryside in 1950. Flavia becomes caught up in a murder mystery when she finds a stranger, who had argued with her father, dying in the family’s cucumber patch. Through an extensive series of investigations, Flavia solves the mystery of the stranger’s death. She also discovers the truth behind the death of her father’s house master, which was thought a suicide but was actually a murder.

Flavia is a remarkably intelligent and precocious girl, whose first love is chemistry, especially poisons. She is extremely lonely, neglected by her father and bullied by her older sisters. Flavia wants them to be a “normal” family, capable of displays of affection and love, but she is constantly disappointed. Flavia mourns her mother Harriet, though she has no memories of her. Mostly Flavia mourns the loss of what Harriet represents for her: the love and affection that is so sorely lacking in her relationship with her father and sisters.

When Flavia finds a dead man in the family garden, she is excited development and welcomes the opportunity to launch an investigation. She is rather flippant about the case, which feels like a game to her.