The devil's hunt - P. C. Doherty

The golden summer of 1303 and Oxford is plunged into chaos. The severed heads of beggars have been tied by their hair to the trees in woods outside the city. John Copsale, the Regent of Sparrow Hall, has been found dead in his bed and it is being whispered that he was murdered by the mysterious 'Bell Man'. Then the college librarian and activist, Robert Ascham is discovered with a crossbow bolt in his chest. King Edward, hearing of the seething unrest in Oxford, arrives unannounced at Sir Hugh Corbett's country manor, and insists that Corbett go to the city to solve the murderous mysteries. And when the King commands, few can resist even if it means knowingly entering a dangerous and violent world...