Ten years after the Black Death, rumours of renewed pestilence revive Cambridge's deepest fears. Disillusioned with clergy and conventional medicine, townspeople turn to charms, pagan rites and the promises of a hidden figure known as the Sorcerer.
Murder, desecrated graves and staged signs of supernatural power strengthen the Sorcerer's influence, while whispers identify Matthew Bartholomew himself as the masked magician. Bartholomew and Brother Michael must expose how the panic is being manipulated before the university and civic authorities lose control—and before the false accusation destroys Bartholomew.