In Rome, Pope Alexander IV lies dying. From the East, an assassin is sent by a powerful royal family. In Wallingford Castle a young man is held prisoner, charged with a murder he did not commit... In the swirling mists of Oxford, Regent Master William Falconer, Aristotelian philosopher and amateur sleuth, searches for the whereabouts of his mentor, Roger Bacon. But a political intrigue is about to explode. The Papal Legate's brother-a master cook-is killed with an arrow during a student riot. While authorities crack down on the disorder and zealots warn of the Apocalypse, Falconer begins an investigation. Now the man of reason must enter a labyrinth or madness-where ambition, deceit, and murder are the order of the day.