Tommy and Tuppence Beresford settle into their newly acquired country house, only to discover a cryptic message hidden within the pages of an antique book—a discovery that may finally expose the truth behind a decades-old poisoning. When underlined letters in a copy of The Black Arrow reveal the name "Mary-Jord," the couple finds themselves drawn into a mystery that questions whether an accident from the past was truly accidental. What begins as an exploration of inherited curiosities transforms into a race to uncover a dangerous secret.
