The story starts by introducing the narrator, Adso. He is the Hollywood version of what a medieval monk would look like, with six-pack abs that an athlete would be proud of. His father has sided with the Holy Roman Emperor against the Pope (Tchéky Karyo - GoldenEye (1995) ), and he has brought the Franciscans into the conflict on his side. . One of the Franciscan Friars, William of Baskerville (John Turturro - Transformers (2007) ), accepts Adso as his companion on his mission.
The Pope has his own favoured band of monks, the Dominicans. They lead his Papal Inquisitions, which wiped out the Cathars and more recently has exterminated some extremist Franciscans led by a man named Dolchino. The head Dominican, Bernardo Gui (Rupert Everett - Inspector Gadget ), is sent on a mission to the same monastery as William. On his way he stops off to persecute some heretics, which creates another sub-plot. A survivor from Dolchino's band wants to avenge herself on the Inquisitor.
At the monastery, a monk has been found dead under suspicious circumstances. The Abbot (Michael Emerson - Lost ) asks William to investigate.