With the debate over, Gui condemns Remigio and the girl to be burnt at the stake. William and Adso try to solve the library's puzzle and catch the killer before it's too late, and Anna makes a final desperate move.
Anna gets better. The Occitan girl gets into trouble. Meanwhile, the debate continues, but is interrupted by another tragic event.
Anna is saved at the last minute. Bernardo Gui's armed entourage arrives at the abbey. After a copious feast, an insidious monk poisons his ears by reporting the presence inside the sacred walls of some former Dolcinian heretics.
After a new tragic event occurs, William and Adso increase their efforts to decipher the mysterious structure of the labyrinthine library, although Adso is more interested in spending time with the Occitan girl.
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.