Abstract: In the two works of Alessandro Manzoni, Les Fiancés and L’Histoire de la colonne infâme, the shared historical backdrop – the plague of Milan from 1629 to 1631 – is constructed with the help of three complementary conceptions of epidemics, based on theories of religion, miasma, and contagion. These visions converge around a sense of the plague as the evil poison par excellence.