William discretely overlooks Adso's time spent with the peasant lay slut and works on a code to read the Apocalyptic verses on the library frescoes, which he interprets as indications they stem from Dolcino's heresy, which Florence eradicated by sword and pyre. Adso's interest in Dolcino's writings alerts dogmatic monks Benno and Malachia. While the papal troops continue their unrelenting advance, a papal message clears the cardinal and inquisitor Bernardo Gui of sins in advance. Huntress Anna seizes the passage to exact bloody long-overdue revenge for her family's death on Bernardo Gui. (Al)chemical knowledge proves valuable in the bathtub drowning case after inspecting what's missing from the abbey's apothecary stock.