Master William Falconer returns in this chilling and atmospheric medieval murder mystery. - Oxford, January 1273. When Regent Master William Falconer receives a cryptic message from Friar Roger, an old friend whose experimental scientific ideas the church consider heretical, he travels to Paris to find him. On arrival, he discovers his friend has been incarcerated in a friary, and he must work to ensure that his scientific theories are not lost forever. But, unbeknownst to Falconer, King Edward has a task for him – one that will test even the Regent Master's legendary powers of deduction.