Eleven-year-old Flavia de Luce didn’t intend to investigate another murder — but then, Rupert Porson didn’t intend to die. When the master puppeteer’s van breaks down in the village of Bishop’s Lacey, Flavia is front and centre to help Rupert and his charming assistant, Nialla, put together a performance in the local church to help pay the repair bill. But even as the newcomers set up camp and set the stage for Jack and the Beanstalk, there are signs that something just isn’t right: Nialla’s strange bruises and solitary cries in the churchyard, Rupert’s unexplained disappearances and a violent argument with his BBC producer, the disturbing atmosphere at Culverhouse Farm, and the peculiar goings-on in nearby Gibbet Wood — where young Robin Ingleby was found hanging just five years before.

It’s enough to set Flavia’s detective instincts tingling and her chemistry lab humming. What are Rupert and Nialla trying to hide? Why are Grace and Gordon Ingleby, Robin’s still-grieving parents, acting so strangely? And what does Mad Meg mean when she says the Devil has come back to Gibbet Wood? Then it’s showtime for Porson’s Puppets at St. Tancred’s — but as Nialla plays Mother Goose, Rupert’s goose gets cooked as the victim of an electrocution that is too perfectly planned to be an accident. Someone had set the stage for murder.

Putting down her sister-punishing experiments and picking up her trusty bicycle, Gladys, Flavia uncovers long-buried secrets of Bishop’s Lacey, the seemingly idyllic village that is nevertheless home to a madwoman living in its woods, a prisoner-of-war with a soft spot for the English countryside, and two childless parents with a devastating secret. While the local police do their best to keep up with Flavia in solving Rupert’s murder, his killer may pull Flavia in way over her head, to a startling discovery that reveals the chemical composition of vengeance.