In March 1944, as World War II rages on, the Old Bailey in London becomes the center of a sensational trial that captures the public's imagination. Four individuals, including Edward and Mrs. Homer, are charged under the Witchcraft Act of 1735, a law that had long been forgotten but now resurfaces amidst the chaos of war. The Homers run a small spiritualist shop in Portsmouth, where they hold seances featuring the famous medium Helen Duncan. The trial draws attention not just for its unusual charges but for its implications on freedom of belief during a time of national crisis.