The death of Malachi shows everyone that the investigations carried out by Bernardo Gui have not served to unravel the mysteries that surround the abbey. Adso does not give himself peace for the girl's fate and asks William to do everything to help her. Baskerville decides to talk to the inquisitor, who initially seems to be listening to him but has actually already made a decision. After a hard confrontation with the abbot, the English monk has no choice but to solve the enigma of the "Finis Africae".