Roman catholic priests poisoned on their thumb fingers

14th-century Franciscan monk William of Baskerville and his young novice arrive at a conference to find that several monks have been murdered under mysterious circumstances. To solve the crimes, William must rise up against the Church's authority and fight the shadowy conspiracy of monastery monks using only his intelligence; which is considerable.

Northern Italy, 1327. The Franciscan monk William of Baskerville and his young apprentice Adso of Melk reach an isolated Benedictine abbey on the Alps to aid in a dispute between the Franciscan Order and the Avignon papacy. Upon arrival at the abbey, the two find themselves involved in a chain of mysterious deaths.