1324. The kingdom is in an uproar. Roger Mortimer—once the king's most able commander, now his most hated enemy—has escaped from the Tower and hired an assassin to murder the monarch. Others have the same idea. In Coventry, a special assassin has been hired: a necromancer by the name of John. But just as his plan begins to succeed, the plot is uncovered. John must escape to a smaller city: Exeter. And when the bodies of a local craftsman and the king's messenger are found in Exeter's streets, Sir Baldwin Furnshill and Bailiff Simon Puttock, are asked by the Bishop to find the murderer. The dead messenger was carrying a dangerous secret, and the Bishop is desperate that it not be discovered. Baldwin and Simon are reluctant to get involved, but political pressures are growing, and the two must find the murderer before he strikes again. But when murderers use magic, no one is safe.