London, 1672. A vicious killer stalks the court of Charles II, inscribing the victims’ bodies with mysterious markings. Are the murders the random acts of a madman? Or the violent effects of a deeply hidden conspiracy? Cambridge, 2008. Teaching history at Trinity College is Claire Donovan’s dream come true --- until one of her colleagues is found dead on the banks of the River Cam. The only key to the professor’s unsolved murder is the 17th-century diary kept by his last research subject, Hannah Devlin, physician to the king’s mistress.

Bess Southerns, an impoverished widow living in Pendle Forest, is haunted by visions and gains a reputation as a cunning woman. Drawing on the Catholic folk magic of her youth, Bess heals the sick and foretells the future. As she ages, she instructs her granddaughter, Alizon, in her craft. When a peddler suffers a stroke after exchanging harsh words with Alizon, a local magistrate, eager to make his name as a witch finder, plays neighbors and family members against one another until suspicion and paranoia reach frenzied heights.