A succession of unexplained illnesses ends in death across Cambridge and the surrounding countryside. Matthew Bartholomew must decide whether the town faces a new contagion or whether someone is deliberately administering poison.
His work is obstructed by an arrogant physician attached to the wealthy Zachary Hostel, whose hostility appears to be professional jealousy but may conceal a deeper interest in the victims. As fear spreads, Bartholomew and Brother Michael trace the pattern of sickness through academic rivalry, local grievances and a plot designed to look like disease.