The town of Oxford in AD 1278 seems a haven of tranquillity. Under the summer sun, merchants, students and clerics go about their daily, unhurried tasks. Alfric, the proctor of the Franciscan friary, has only two minor problems: one of the friars has gone missing, and there's a travelling showman, calling himself the Doctor, with a pretty young noblewoman by his side, attracting crowds in the narrow streets. When the missing friar is found dead, the Doctor is convinced he has been murdered. There is a ruthless killer at large, and Alfric reluctantly teams up with the Doctor to track him down.